8th International Materials Science Conference HighMatTech-2023
October 2-6, 2023 Kyiv, Ukraine
Speakers:
нижче по генерованих топіках
Composite Materials_program_list
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H3-DS1149 |
Effects of thermo-hardening and thermo-plastification at 200-280 oC for microfilled epoxy-composites. Examples for filling by silicon carbide, titanium nitride, gypsum G5 and Cement M400. Dmitro Starokadomsky1, Mariia Reshetnyk2,3 1Chuiko Institute of Surface Chemistry National Academy of Sciences, Ukraina The work is devoted to the study of a new type of composites for the manufacture of special details, parts, tools or adhesive repair in the field. We have developed epoxy compounds that preserve or increase strength and ductility after heating at 200-250 °C.
That let, if necessary, an effective thermo-disinfection of composite toolsproducts at elevated temperatures. It is believed that conventional epoxy resins are unable to retain their physical and mechanical properties after heating above 200 °C. Their feature is in simplicity of making (ordinary filling with available/cheap microfillers) without special qualification of personnel and in any conditions (outside clinics, laboratories and service centers).
In this work some of such compositions (with SiC, TiN, SiO2-marshalite, cement) are considered. It offers to name such composites of “thermo-harden” or “thermo-plasticized”. Bioneutrality, durability and heat-resistance, at 200-300 °C does him a good material for rapid repair and making of the special or failing instruments in the field, travelling, military and other difficult terms.
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Dmitro Starokadomsky |
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H3-OM9451 |
Some principles of creation of multi-layer composite Oleksandr Matviichuk V. N. Bakul Institute for Superhard materials NASU, Ukraine The creation of multilayer compositions with the purpose of obtaining certain functional properties is widely studied [1]. The WC-Co system contains 7 types of microstructures depending on the size of the tungsten carbide grain [2]. The use of other refractory carbides makes it possible to expand the types of microstructures [3]. The combination of different microstructures would make it possible to create compositions with different physical and mechanical properties in terms of volume. In multilayer composites, each layer must perform a certain function: work in bending or have high crack resistance; improve connection between opposite layers, etc. For metal-ceramic materials such as hard alloys, similar studies are not carried out because the selection of the composition is a difficult task. The main application of hard alloys is a cutting tool, mining tool, and friction pairs. Two or three layers are enough for such products in the structure. Because one of the layers should have a high modulus of elasticity, and the other should have fatigue strength.
The creation of multilayer microstructures is limited by the speed of diffusion and migration processes during liquid-phase sintering [4]. Taking into account the peculiarities of the interaction of components with each other, the principles can be formulated, which will allow creating multilayered compositions: composites must have a low melting point or a high sintering rate; the type of binders, their amount should be similar in composition and quantity; the formation of the composition should be carried out by alternating a high-modulus layer with a low-modulus one, to ensure liquid phase migration; the arrangement of the layers should al-ternate in such a way that the high-modulus layer is on the bottom, and the low-modulus layer is on top; the minimum number of layers in the composition is 2-3; the thickness of the layers is determined by the stresses between the layers and working conditions.
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Oleksandr Matviichuk |
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H3-OB1712 |
Features and theoretical analysis electric and thermoelectric properties of Со/Al2O3, Со/SiO2 and Co/TiO2 ferromagnetic nanocomposites in the low-temperature region Oleksii Baibara1, Mykhailo Radchenko1, Arsenii Ievtushenko1, Yaroslav Stelmakh2, Larysa Krushynska2, Tatiana Zajarniuk3, Tomashz Story3 1I.M. Frantsevych Institute for Problems of Material Science, National Academy of Sciences of Ukraine Ferromagnetic nanocomposites (FMNC), consisting of ferromagnetic nanoparticles distributed in a dielectric matrix, occupy a special place in the class of granular materials with a wide range of potential applications. Granular structure determines the specific properties of FMNCs, in particular, the metal–insulator transition induced by a change in metal content x, so below percolation threshold, the metallic granules in ferromagnetic nanocomposites are separated by dielectric layers, and hopping transport (VRH) to be predominant. Ferromagnetic nanocomposites with Co nanoparticles distributed in various dielectric amorphous matrixes Al2O3, SiO2 and TiO2 were grown by the EB-PVD method in the form of film with thickness from 0.8 to 10 μm on Al2O3 substrates (polycor). The Cо concentration x varied in wide region from 10 to 70 at.% for all matrixes.
The temperature dependences of the resistance for FMNCs Co/Al2O3, Со/SiO2 and Co/TiO2 were investigated in the temperature range of 77 ÷ 290 K. Samples of FMNC were fitted by formula ρ =ρ0exp(T0/T)n. For FMNCs best fit corresponds to the value of n~0.75 and the results are discussed in terms of several different models of hopping conduction.
For FMNCs Co/Al2O3and Co/TiO2 samples with Co concentration below the percolation threshold are characterized by an increasing of thermoelectric power when the magnetic field is turned on.
Temperature dependences of thermoelectric power (α) of the form α(T)~1/T and α(T)~√T +T are typical for VRH modes, and α(T)~T typical for metals, do not describe experimental results for FMNC below percolation threshold. An empirical formula for the temperature dependence of thermoelectric power was presented in form α(T)~1/Tn +T where n depends from concentration of Co and the presence of the magnetic field.
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Oleksii Baibara |
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H3-SI2126 |
Effect of crystallization properties of continuous basalt fibers on thermal stability of composite materials Stanislav Ivanitskii, Yurii Chuvashov Frantsevich Institute for Problems of Materials Science, NAS of Ukraine The thermal stability of composite materials is determined by the strength of basalt fibers under thermal stress. The strength decreases as a result of the development of microcrystalline nuclei, which formed in the original fibers during drawing. The aim of this work is to analyze the effect of treatment temperature on the strength of basalt fibers and substantiate the conditions for reducing the development of the crystalline phase at the fiber drawing. Fibers were obtained on a laboratory bench. The diameter of the fibers was determined an optical microscope. Heat treatment of fibers was carried out in a muffle furnace in the temperature range of 200-700 °C. The strength of the fibers was studied on a breaking machine. The temperature of the upper limit of melt crystallization was determined by the quenching method. The glass transition temperature Tgl and crystallization time were determined using numerical methods. The strength of fibers during heat treatment up to 400 °C decreases by 25 % from the initial one. At a temperature of 500 °C, the strength of the fibers is almost halved. At 600 °C, the fibers strength is 20 % of the initial strength. At 700 °C, the fibers are completely destroyed. During fiber drawing, microcrystalline nuclei are formed in the crystallization zone. From above, this zone is determined by the temperature of the upper limit of melt crystallization, and from below it is limited by the Tgl. The residence time of the melt in this range is the crystallization time. Calculations the speed of movement and the cooling rate of the melt jet during fiber drawing were carried out, which made it possible to determine the temperature zone and time of crystallization. The results of theoretical studies have shown that for the production of fibers used in composites, it is necessary to select such basalts and conditions for the fiber drawing, under which the values of the temperature zone and time of crystallization will be the smallest.
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Stanislav Ivanitskii |
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H3-KP1509 |
Cyclic Heat Resistance and Peculiarities of Oxidation of Nickel Reactive Sintered Alloys Viktor Solntsev, Gennady Bagluk, Tetiana Solntseva, Kostiantyn Petrash, Alevtina Mamonova, Galina Molchanovsky Frantsevich Institute for Problems of Materials Science, Ukraine Interest in the problem of creating new heat-resistant nickel superalloys is of particular importance in connection with the problems of developing reusable hypersonic and space technology. The most promising direction is due to the creation of technologies for nano-hardened powder materials using reactive sintering technology, which allows the introduction of additives of rare-earth metal oxides. Reaction sintering makes it possible to effectively use the influence of irreversible reaction interaction processes on the consolidation and formation of a directionally organized structure of the materials [1].
The study of the processes of cyclic oxidation was carried out according to a scheme that displayed conditions close to the requirements for heat-shielding materials intended for operation with aerodynamic heating. Evaluation of heat resistance was carried out according to the weight gain of the samples for each cycle. The nature of heat resistance was evaluated based on the analysis of the phase composition of the formed protective film by XPA.
The studies have shown that the maximum weight gain of samples alloyed with more than 6% aluminum is observed in the first two cycles, after which the weight change was within the error of the analytical balance. With this content, alloying with molybdenum, tungsten, niobium and titanium is allowed without a significant loss of heat resistance. The study of the phase composition showed that the composition of the oxide film is represented mainly by aluminum oxide and, in a small amount, by nickel oxide. However, the diffraction maxima from the main lattice planes of the nickel-based solid solution have the highest intensity, and some amount of aluminum intermetallic compound is also present. From this it can be concluded that the alumina film is quite thin, but it determines the oxidation resistance most effectively.
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Kostiantyn Petrash |
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Poster session Important.session is online-only and include 5 min presentation in the common conference room and 1 hour of discussion in individual rooms (Zoom) |
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H3-MZ1718 |
Advanced Nanocomposites TiO2-Ag for Viruses Remediation Maksym Zahornyi1, Olena Lavrynenko1, Nadya Tyschenko1, Andrey Ragulya1, Olga Povnitsa2, Liubov Artiukh2, Svitlana Zahorodnia2, Arsenii Ievtushenko1 1I.M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine At present, nanocomposites TiO2&Ag are a class of nanomaterials suitable for photocatalysis, photochemical cells, etc. The aim of the work was the synthesis of TiO2-Ag systems to test their antiviral activity in an organic medium. The formation of the nanocomposites was presented via the TiO2 (metatitanic acid) modification by the Ag with a concentration of 4.0 and 8.0 wt.%. The systems were washed, filtered, lyophilized at 120 °C and calcined at 600 °C. TiO2-Ag particles were studied by XRD, SEM, and EDS methods. Lattice parameters were: a – 0.3785÷0.3787 nm, c – 0.9522÷0.9519 nm; CSR of pure TiO2 was 14.0 nm, and CSR of the nanocomposites 12.0-13.5 nm, respectively. Therefore, Ag as a doping element in TiO2 can promote the formation of an optically active anatase structure. The photocatalytic activity of the nanomaterials was tested by Xe-lamp of 300W power using a phenol solution (50 mg/dm3). The degree of phenol destruction was 70% after 20 min of contact with TiO2-Ag (4wt.%) compared to pure TiO2. As such, photogenerated electrons can accumulate on the surface of Ag and transfer to O2 molecules and chemisorbed on the surface of TiO2 following ROS formation to remediation of pollutant. We evaluated the possibility of using photodynamic ultraviolet treatment of synthesized TiO2&Ag nanocomposites to inactivate human adenovirus type 5. The suspension of TiO2&Ag (concentration 1 mg/ml) was irradiated for 30 min with UV light (Bactosfera OBB 15P, Poland) at a distance of 20 cm, with a wavelength of 254 nm. Virus-containing material with a titer of 4.0 log10 TCID50/ml was added to the nanocomposites and cells were infected. It was stated that the inactivation of adenovirus by UV-photoactivated nanoparticles led to a decrease in virus titer by 3.8 log10 TCID50/ml. Thus, the obtained photocatalytic active nanostructures are promising materials for biomedical applications.
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Olga Povnitsa |
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H3-OM1956 |
Nanostructured materials compacted via hot pressing method by direct current transmission Edwin Gevorkyan1, Oksana Morozova1, Chyshkala Volodymyr2, Volodymyr Nerubatskyia1 1Ukrainian State University of Railway Transport, Ukraine Nanostructured ceramics have unique properties and performance characteristics due to the formation of a fundamentally different structure compared to their large-crystal counterparts. The most important stage in the technology of nanoceramics production is the formation of quality pressings (compacts) of a given shape made of ceramic nanopowders. NPs of ceramic compositions (often very complex) have a metastable structural-phase state, a developed specific surface and as a consequence, high surface activity and tendency to agglomerate.
Pre-prepared tungsten carbide tablets were hot-pressed in a vacuum of 10-2 mmHg. Maximum pressure for graphite PG-7 is about 50 MPa at a temperature higher than 1200С, so the maximum force for the given mould with a punch d=20 mm is 45 MPa. Temperature of termination of shrinkage has made 1700С. The density of pressings after grinding was determined by hydrostatic weighing. Rockwell HRA hardness was determined by indenting a diamond pyramid on the TM-12.
During high-temperature sintering under load the WC grain size increased insignificantly, remaining mostly less than 1 μm. At the same time there is practically no porosity in the materials. That is why high values of σvizr = 720 MPa were obtained. In our case, a high value of fracture toughness K1c, which is important for cutting tool ceramics, can also be expected with a high value of HRA. The increase of fracture toughness of such material can be explained on the basis of the known model of increase of K1c in polycrystalline materials, namely by the joint action of two factors: highly dispersed grains and low strength boundaries both between grains below 1 µm and between coarser ones.
To conclude, the method of hot pressing under direct current flow makes it possible to obtain high-density nanoporous tungsten carbide products with high physical and mechanical properties.
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Oksana Morozova |
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H3-OK1221 |
Bulk electrical resistance and electromagnetic energy absorption of pressureless sintered aluminum nitride ceramics Igor Fesenko1, Vasyl Chasnyk2, Oksana Kaidash1 1Bakul Institute for Superhard Materials National Academy of Sciences of Ukraine The creation of aluminum nitride based materials AlN–Mo and AlN–SiC, which perfectly absorb electromagnetic energy, is necessary and important for the development of new vacuum electronic microwave devices
To provide the stable operation of a travelling wave tube (TWT) with a delay system (DS) on a coupled-resonator chain (CRC) with a high output power, the bulk microwave energy absorbers must have not only high absorption and heat conductivity, but also the corresponding electrical resistance.
30 rings Ø16×Ø6×2.6-mm manufactured from the AlN–50%SiC composite were sintered to a high-density state The electrical resistance was measured with an UT 30D digital multimeter. Afterwards, the rings were divided into 5 groups differed from each other more than 100 Ω. They were additionally sintered at 1850, 1900, and 1950°C (holding 1 h) and more 1950°C (1 h). After each sintering, the measurements on the electrical resistance and electromagnetic energy absorption for the rings was repeated.
When the sintering temperature is increased from 1800 to 1950 °C, the absorption grows by 1.76 times, but the corresponding electrical resistance value becomes lower for all the studied AlN–SiC composites within a range of primary resistances from 3.2 to 6.8 kΩ.
The bulk resistance of AlN–50%SiC composite rings must be 2–4 kΩ cm to provide the maximum absorption of 11.7–12.5 dB
Conclusions.
For AlN–SiC composites, the electromagnetic energy absorption grows by 1.76 times when the sintering temperature is increased from 1800 to 1950 °C. At the same times, the preferential range of change in the electrical resistance is Rsp = (1.3–2.7) × 104 Ω cm.
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Igor Fesenko |
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H3-VB0302 |
Optimization of the composition and structure of carbon fiber preforms for carbon-carbon composite materials Oleksandra Mazna, Viktoriia Bezsmertna, Yurii Vasylenkov, Nataliia Hohlova, Valentyna Danyliuk Frantsevich Institute for Problems of Materials Science NASU, Ukraine The use of new types of reinforcing fiber preforms for gas phase infiltration process in the carbon-carbon composite technology (CCC) is complicated by the unique structure and high damage of carbon fibers (CF), especially high-strength CFs from PAN (polyacrylonitrin threads).
This work aims to optimize the composition and structure of fiber preforms for carbon-carbon composite materials based on knitted fabrics using carbon fibers from PAN and cellulose fibers.
Optical microscopy has shown that the CCC structure inherits the main features of the original structure and has a characteristic stacking of CFs and texture depending on the type of CFs used. The structure of the fiber preform and the system of transport pores (interlayer, interfiber, interfilament) contribute to the homogeneous formation of the carbon matrix in CCC during gas-phase deposition of pyrolytic carbon. The density of CCC obtained based on preforms from cellulose-derived carbon fibers (CFs) was 1.57-1.63 g/cm3, and with the content of CFs from PAN - 1.70-1.73 g/cm3.
Technology has been developed to manufacture a reinforcing filler in the form of a weft-knitted fabric, in which high-strength CFs from PAN are laid with a straight thread, i.e., not bent by knitting machine needles to form buttonholes. The use of carbon weft-knitted fabrics for the manufacture of preforms for the gas phase infiltration process makes it possible to provide the necessary anisotropy of properties through the spatial arrangement of fibers and stitching layers of knitted fabrics with carbon thread in the transverse direction (2D + 1) provides interlayer connection of reinforcing elements and improves the wear resistance of preforms and CCC.
The tribotechnical properties of the developed CCCs determined by the thermal impulse friction regime meet the criteria for aircraft brake materials. The friction coefficient of the obtained CCC was found to be 0.32-0.35, and the linear wear was 0.37-0.88 µm/braking.
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Viktoriia Bezsmertna |
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H3-RL1948 |
Mechanosynthesis of disperse composite powders based on TiB220MeSi2 and TiB220MeC systems (where Me – Ti, Nb) Iryna Kud, Larysa Krushynska, Roman Medyukh, Ostap Zgalat-Lozynskyy, Roman Lytvyn Frantsevich Institute for Problems in Materials Science of NAS of Ukraine The aim of the work is to study the formation of structure and phases of composite powders in TiB2-20 wt% MeSi2 and TiB2-20 wt% MeC systems (Me - Ti, Nb) in mechanosynthesis. Our studies of the mechanosynthesis of carbides, borides, and silicides of transition metals showed that compounds with an adiabatic temperature ≥1800 K form by the mechanism of mechanically stimulated reaction (MSR).
The mechanosynthesis was performed in an AIR high-energy planetary mill in an argon atmosphere in two directions: synthesis of the individual phases TiB2, TiSi2, NbSi2, TiC, and NbC; mechanosynthesis with the use of two types of reaction mixtures: Ti+B+Mе+Si and Ti+B+МеSi2 or Ti+B+МеC.
It was shown that, in synthesis of composite powders in the TiB2-20 wt% MeSi2 and TiB2-20 wt% MeC systems (Me - Ti, Nb), interaction occurred by the MSR mechanism and enabled us to obtain ultradisperse powders with 3-8 µm agglomerates, which consisted of finer particles with a size <200 nm. In synthesis from elements (Ti+B+Si and Ti+B+Nb+Si), the final products are a TiB2-based matrix phase and lower silicides (Ti5Si3 or Nb5Si3). In synthesis from the Ti+B+С and Ti+B+Nb+С reaction mixtures, the final products are a TiB2-based phase and traces of Ti or Nb.
The synthesis from the mixtures containing Ti+B and preliminarily synthesized compounds TiSi2, NbSi2 or TiC, NbC leads to the synthesis of a two-phase composite material.
We can conclude that, in the case where components of the composite material have different exothermicity levels of the reactions of their formation, it is reasonable to use a mechanosynthesized compound with a lower adiabatic temperature (TiSi2, NbSi2, TiC, and NbC).
Developed disperse composite powders can be applied for the production of high-temperature ceramics and protective coatings with an improved complex of physicomechanical properties for structural applications, cutting tools, armor, electrodes in metal smelting, and heavy-duty wear applications.
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Larysa Krushynska |
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H3-GS2343 |
The Role of Cell Collapse Mechanism in Mechanical Performance of Aluminium Foam Fabricated by Melt Processing Alexandra Byakova1, Svyatoslav Gnyloskurenko2, Andrey Vlasov1, Yan Yevych1, Nikolay Semenov1 1Frantsevich Institute for Problems of Materials Science of National Academy of Sciences of Ukraine Closed-cell aluminium foams show alluring potential for different engineering application mostly due to significant energy absorption. The foams are also considered to be important as integral ceramic/metal/synthetic composites used for ballistic and blast protection of terrestrial vehicles. Nowadays efforts are concentrated on the search of parent aluminium alloys with foaming additives to realize proper collapse mechanism under load and promote increased energy absorption.
The study presents mechanical performance metrics, especially, energy absorption, of foams fabricated by melt processing with CaCO3 blowing agent by employing relatively ductile Al1Mg0.6Si alloy and high strength Al6Zn2.3Mg alloy comprising brittle eutectic domains. Microstructure of cell wall material of the foams was examined by using scanning electron microscopy. Mechanical testing of foamed specimens was realized under uniaxial quasi-static compression in line with ISO 13314:2011.
Compression curves for the foams with wide range of relative density (0.09-0.3) were determined and analysed. It was recognized that response of the foams and energy absorption is radically defined by mechanism of cell collapse which, in turn, depends on the nature of structural constituents of the cell wall material. In particular, elastic-plastic cell collapse is typical for the foam based on Al1Mg0.6Si alloy. As opposed to this, the presence of brittle eutectic domains in the cell wall material of Al6Zn2.3Mg alloy stimulates contribution of failure to cell collapse, which impair the strength. The foam based on Al1Mg0.6Si alloy demonstrates higher energy absorption compared to that of Al6Zn2.3Mg alloy when relative density exceeds 0.14. In addition, energy absorption at the end of deformation plateau Wpl is found to be greater than the value W50 at 50% deformation. The experimental verification of foams cell collapse is considered to be strongly required before their engineering application.
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Svyatoslav Gnyloskurenko |
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H3-OK1900 |
Synthesis of ordered perovskite-type LaLuO3 nanopowders Yuriy Yurchenko, Oksana Korniienko, Marina Zamula, Tamara Tomila, Oleksandr Shyrokov Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine In recent years, materials based on phase-ordered perovskite-type LaLuO3 have been extensively studied depending on their physical and chemical properties. These are very promising for laser and scintillation media applications due to their high optical transparency in a wide radiation range, chemical and radiation resistance, high thermal conductivity and thermal stability, and appropriate thermomechanical properties.
For synthesizing the nanomaterials was used the Peccini method. The synthesized precursors and their thermal decomposition products were studied using several physicochemical methods, such as infrared spectroscopy, X-ray diffraction, and microstructural analysis.
This study develops a synthesis methodology for the ordered perovskite-type LaLuO3 nanopowders. XRD analysis has shown that the diffractograms of the obtained samples contain exclusively diffraction peaks corresponding to the ordered perovskite-type phase. The microstructural studies revealed that the obtained nanomaterial is monocrystalline, which is also confirmed by the results of IR-spectroscopy. And moreover confirmed the insignificant presence of carbonyl and hydroxyl functional groups (>CO and -OH). The lanthanide oxides (especially lanthanum oxide) have a significant tendency to attach water and carbon dioxide from the air, which results in the IR spectra of these compounds containing absorption peaks of -O-H, >C=O bonds and carbonate anions CO32-. The weak intensity of these peaks suggests that the above groups are predominantly present on the surface rather than in the bulk volume of the crystals. Technological conditions optimizations, focused on reducing the aggressive effects of the environment alongside the phase formation control at the stages of nanoparticle synthesis and material production, will help to influence the chemical purity of the obtained materials.
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Yuriy Yurchenko |
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H3-AS1822 |
Hydroxyapatite-based composites modified by magnetite and chitosan as a magnetic material for medical application Anna Synytsia1, Olena Sych1,2, Anatolii Perekos3, Tatiana Babutina1, Iryna Kondratenko1 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Magnetosensitive composites based hydroxyapatite (biogenic (BHA) or synthetic) modified by magnetite particles and chitosan are promising materials for control and delivery of drugs under the influence of an external magnetic field, which could contribute to the regeneration processes of bone tissue damage.
BHA / magnetite / chitosan composite powders based on magnetite obtained by chemical precipitation for 5 minutes and thermolysis in a nitrogen medium with different ratios of components (wt. % BHA / magnetite: 99/1, 95/5, 75/25, 50/50 with a chitosan content of 0.1%) were used as test materials.
Magnetic properties, namely specific saturation magnetization and residual saturation magnetization were evaluated using a ballistic magnetometer “BM-1 IMF” at room temperature in the range of fields up to 1 T.
According to the obtained results it was established that not only the amount of magnetite affect the magnetic properties of composite materials, but also the type (synthesis method). Composites containing magnetite obtained by thermolysis have higher values of saturation magnetization. Thus, the maximum specific saturation magnetization was 40.2 A·m2/kg for the material with 50% magnetite content. At the same time, the minimum value was 0.72 A·m2/kg for the material with 1% magnetite content. The residual magnetization saturation was 0.5 A·m2/kg and 0.14 A·m2/kg, respectively. As for composites containing magnetite obtained by chemical precipitation, the values of saturation magnetization for these materials are somewhat lower. The maximum specific saturation magnetization was noted 22.1 A·m2/kg for a material with 50% magnetite content and the minimum was 0.14 A·m2/kg for material with 1% magnetite content, as well as the residual saturation magnetization was 0.31 A·m2/kg and 0.01 A·m2/kg, respectively.
Therefore, taking into account the obtained results, BHA / magnetite / chitosan composites can be used as magnetic materials for medical applications.
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Anna Synytsia |
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H3-VS1510 |
Destruction of spacecraft polymer films under exposure to high-velocity atomic oxygen flows Valentin Shuvalov, Nikolai Gorev, Galina Kochubei, Yuri Kuchugurnyi, Nikolai Pismennyi, Nikolai Tokmak Institute of Technical Mechanics (ITM) of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine Polymers are widely used in spacecraft as structural materials: outer coatings, structural components of blanket thermal insulation, solar array coverings, etc. In near-Earth orbits (200 km – 700 km), polymer exposure to high-velocity atomic/molecular plasma flows – 5 eV atoms and atomic ions – results in polymer surface sputtering and degradation. In spacecraft designing, materials are selected on the basis of their resistance to long-term exposure to the near-satellite environment, in particular to atomic oxygen (AO) flows, determined from the results of life tests on dedicated setups and material exposure onboard spacecraft.
The goal of this work is to substantiate a methodology and develop procedures for accelerated life tests of polymer films for resistance to long-term exposure to high-velocity AO flows. Experiments were conducted on the ITM plasmaelectrodynamic setup, which has the status of the National Heritage of Ukraine. Polymer samples were exposed to an AO plasma beam followed by the determination of the mass loss and the film surface profile and erosion depth. Surface destruction was studied using an optical microscope and a scanning atomіc-force one.
The polymer sputtering yields, surface roughness, erosion depth, and solar absorptance are determined as a function of the AO fluence over a wide range of the AO ion energy (5 eV – 264 eV) and fluence (10^16 ionO/cm^2 – 10^21 ionO/cm^2) using the results of satellite tests in the Earth’s ionosphere and laboratory tests. A methodology is substantiated and procedures are developed for accelerated life tests of polymer films for resistance to long-term AO ion exposure on dedicated setups using 5 to 100 eV AO ions. The life test time acceleration factor is determined as a function of the AO ion fluence and energy using Kapton-H polyimide as the reference material.
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Valentin Shuvalov |
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H3-IG1505 |
Wear peculiarities of in situ Ti-Si-Sn composites with reduced elastic modulus under different friction conditions Iryna Gorna, Katerina Valuiska, Konstantyn Grinkevych, Olexandr Koval, Sergiy Firstov Frantsevich Institute for Problems of Materials Science NAS of Ukraine One way to improve the limited wear resistance of Ti alloys is to produce heterophase (composite) structures. In situ Ti–Si–Sn metal-matrix composites can be attributed to such materials. In addition, unusual mechanical behavior is observed for these alloys, which is associated with the features of plastic deformation in the temperature range of the thermoelastic martensitic transformation of α2Ti3Sn phase.
The aim of this work is to study the tribotechnical properties under different friction conditions of selected Ti-Si-Sn alloy compositions with elastic modulus varying from 124 to 37 GPa.
Wear tests were performed on the tribodynamic complex with a dynamic loading module according to the "sphere-plane" scheme. In the process of reciprocating sliding under both of the quasistatic and dynamic mode with the effective load of 30 N the tribology tests the surface of flat Ti-Si-Sn alloys samples vs the spherical ceramic Si3N4 indenter (ᴓ 8 mm) were carried out. The way of friction was ~17.64 m for test duration of 1200 s. Linear wear was determined by the profilograph−profilometer "K-201".
Five eutectic Ti−Si−Sn alloys were studied, the content (Si+Sn) in which increased from 13 to 28 at. %. It’s led to changes in the phase composition of the alloys with a replacement of αTi− matrix with the intermetallic one α2Ti3Sn. The Vickers hardness of alloys decreased from 4.32 to 2.56 GPa, and the elastic modulus from 124 to 37 GPa.
It was established that Ti−Si−Sn alloys with αTi−matrix with the highest values of hardness and elastic modulus shown not the good wear resistance and more high friction coefficient compared to alloys where the matrix was α2Ti3Sn. In contrast, the latter alloys, unlike steels and cast irons, were more adapted to friction under dynamic loading regime than under quasistatic loading. The linear wear of samples of such alloys is 2-3 times less compared to other Ti−Si−Sn alloys because of a high damping capacity due to their low elastic modulus.
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Konstantyn Grinkevych |
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H3-IG1549 |
Temperature Dependence of Hardness and Plasticity of Aluminum Matrix Composites (AMC) of the Al-Fe-Cr System Svitlana Chugunova, Mykola Iefimov, Oleksii Golubenko, Nataliia Zakharova, Irina Goncharova, Oleksandr Lukianov Frantsevich Institute for Problems of Materials Science, NASU, Ukraine The aim of the work was to study the mechanical behavior of the AMC of the Al-Fe-Cr system (hardened by nano-quasi-crystalline and/or crystalline phases) in the temperature range of -196...300 °C by the indentation method.
Due to the fact that nanostructured quasicrystals (NQC) have some plasticity at room temperature, they are well suited for hardening AMC composites capable of operating at temperatures up to 300°C.
For the study, composite alloys of the Al-Fe-Cr system of the following chemical (phase) composition were selected: 1 - Al94Fe2,5Сr2,5Ti1 (Al+crystalline intermetall Al13(Fe,Cr)2-4; 2 - Al94Fe2,5Cr2,5Ti2 (Al+Al23Ti9+NQC); 3 - Al94Fe2,5Сr2,5Ti0,7Zr0,3 (Al+NQC).
The maximum value of microhardness HV = 2.25 GPa was obtained for alloys 2 and 3 at liquid nitrogen temperature. With increasing temperature, HV for these alloys gradually decreased and at 300 °C the hardness value is 1.57 GPa. In contrast to alloys 2 and 3, the HV for the 1st alloy is lower in the entire temperature range and at 300 °C HV=1 GPa.
In the previous works of the authors, it was shown that for the case of single-phase materials and low-alloys, the plasticity values from hardness measurements (δН) quite well agree with the plasticity values (δ,%), obtained from standard mechanical tensile and compression tests.
The studied AMCs are a multicomponent materials, therefore, the determination of plasticity by the indentation method δН makes it impossible to take into account the effect of each phase on the mechanical properties of the composite. The obtained values of δН for all three alloys are approximately the same and amount to ~0,85.
Therefore, standard tensile tests were performed with the determination of plasticity δ,% at room temperature. It is shown that alloy 1 has a minimum plasticity of δ~1% compared to alloy 2 and 3, for which δ~7%.
Thus, for ensuring high plasticity of AMC based on the Al-Fe-Cr system it is necessary to use NQC particles with an icosahedral structure.
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Svitlana Chugunova |
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H3-VB1701 |
Electrical conductivity of composite materials based on n-InSe and thermally expanded graphite Volodymyr Boledzyuk, Kamiskii Vasyl, Tkachuk Ivan, Tovarnitskii Mircha, Zaslonkin Andriy Frantsevych Institute for Problems of Materials Science of National Academy of Sciences of Ukraine, Chernivtsi Branch Composites based on carbon materials (graphite, thermo-expanded graphite (TEG), graphene, activated carbon) and semiconductor compounds make it possible to create materials with alternate areas of micro- and nanometer sizes such as semiconductor-dielectric-semiconductor. It is of some interest to investigate the properties of composite compounds based on materials related in structure, but different in their electrophysical properties, in particular graphite/TEG and layered semiconducting InSe and GaSe. Such compounds can be promising materials for thermo- and photoelectronics.
The pressed samples of the initial InSe and TEG powders had n-type electrical conductivity, which at T = 285 K was 1.2∙10–7 Ω–1∙cm–1 and 1220 Ω–1∙cm–1, respectively. In order to determine the percolation threshold, samples with different TEG content (х = 4, 8, 12, 16 wt.%) were studied. In the region of TEG content 0 < x ≤ 4, in the investigated samples, the value of σ increases by more than 9 orders of magnitude. This confirms the percolation character of electrical conductivity due to the flow of current through the conductive channels of contacting graphite grains, which form a percolation cluster. The analysis of the temperature dependence of σ revealed the value of the percolation threshold xs ≈ 0.5 for the InSe-graphite composite.
From the analysis of the temperature dependences of the electrical conductivity, the model of activation conductivity in the region of T < 250 K was confirmed, and the activation energy Ea was determined for the TEG-InSe samples (16 wt% TEG).
In the region of T > 250 K, the conductivity of the samples determines the barrier mechanism of current flow along the boundaries of crystallites. The height of the barrier at the grain boundaries Eb is 34 meV and 19 meV, respectively, for TEG and TEG-InSe (16 wt. % TEG).
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Volodymyr Boledzyuk |
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H3-IS2217 |
Structure and thermal stability of Ga-In-Sn matrix nanocomposites Ihor Shtablavyi, Yuriy Kulyk, Mykhailo Klepach, Yuriy Plevachuk, Stepan Mudry Ivan Franko National University of Lviv, Ukraine Gallium-based eutectic alloys are of great practical importance due to their low melting point and wide temperature range of existence of the liquid phase. In particular, the gallium-indium binary eutectic alloy has a melting point of 15.7 C, and the ternary Ga-In-Sn eutectic alloy (so-called Galinstan) melts at a temperature of -19° C, and its boiling point is more than 1300° C. These alloys also have good thermal and electrical conductivity, so they are often used as thermal interfaces and conductors for flexible electronics at room temperature.
The addition of nanoparticles to melts changes their physical properties. First of all, this applies to the already mentioned thermal conductivity and electrical conductivity, as well as other properties, and in particular – viscosity or fluidity. Of particular interest is the effect of ferromagnetic nanoparticles on the possibility of changing the magnetoresistance of composites, which will allow creating flexible magnetic field sensors based on them.
However, due to the significant reactivity of melts, there is a possibility of dissolution of nanoparticles in the liquid matrix, which will cause undesirable changes in the properties of nanocomposites. In this regard, our work investigates the stability of composites with Ga-In-Sn liquid matrix and Co-Fe (or Ni-Fe) based nanoparticles as filler. Composites were synthesized by the method of mechanical mixing of nanoparticles with melt. Nanoparticles of CoFe2O4 (NiFe2O4) and hydrogen reduced nanoparticles were used as nanofiller.
The thermal stability of nanocomposites was studied by the method of differential thermal analysis in a vacuum and in a hydrogen atmosphere. The phase composition of the alloys was studied by X-ray diffraction. In addition, the influence of the phase composition of the composites before and after heat treatment on their magnetoresistance was studied.
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Ihor Shtablavyi |
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H3-SK1039 |
Effect of free carbon content in the WC@C electrolytic composite on its catalytic characteristics in the hydrogen evolution reaction Serhii Kuleshov1, Inessa Novoselova1, Anatolii Omel’chuk1, Valerii Bykov2 1V.I. Vernadsky Institute of General and Inorganic Chemistry, Ukraine Tungsten carbides and their various composites can replace Pt-based catalysts for Hydrogen Evolution Reaction (HER). High-temperature electrochemical synthesis (HTES) makes it possible to obtain WC powders with high specific surface area. To obtain a composite WC@C without impurities (W, WO₃ or W₂C) by the HTES method, it is necessary to have free carbon in mixture.
The relationship between the carbon content in a WC@C and its performance as a cathode material of HER in acidic solution have been shown in the presented paper.
WC powders with different carbon content were obtained by electrolysis of molten NaCl–KCl (1:1) using various precursors (Na₂WO₄, Na₂W₂O7, CO₂, Li₂CO₃) at 750 °C. The properties of products were studied by XRD, BET, SEM and Raman spectroscopy. The electrocatalytic testing of graphite electrode, the end of which was coated with catalytic ink from as-prepared WC@C, was carried out at 21 °C in solution of 1N H₂SO₄ in a standard three-electrode cell.
Electrocatalytic testing has shown that WC with 5 wt.% carbon exhibits much better performance for HER with low initial potential (-0.05 V vs. SHE), overvoltage (-0.2 V at 20 mA/cm²) and slight Tafel slope (-57 mV/dec) compared to 3 wt.% carbon WC (-0.1 V; -0.25 V; -82 mV/dec) and non-carbon WC (-0.15 V; -0.3 V; -91 mV/dec). The results obtained can be explained by the following reasons. Firstly, the surface area for the composite WC@C (5 wt.%) is 140 m²/g, for WC@C (3 wt.%) and carbon-free WC are 50 and 25 m²/g, respectively. That is, catalysts with higher carbon content have a larger surface area, which increases the number of active sites available for HER. Secondly, according to the SEM, the WC particles are wrapped with free carbon. The formation of such structure contributes to the protection of the WC from oxidation to WO₃, which is less active.
In conclusion, our study has shown that the presence of free carbon in WC@C composite catalysts has a positive effect on their catalytic activity in HER.
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Serhii Kuleshov |
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H3-SK1526 |
Mechanical and tribological properties of powdered aluminum-matrix composites obtained by hot plastic deformation Stepan Kyryliuk, Yevheniia Kyryliuk, Yulia Shishkina Frantsevich Institute for Problems in Materials Science, NASU, Ukraine The mechanical and tribological properties of aluminum-matrix composite materials reinforced with titanium carbide during their synthesis and consolidation by hot forging is studied. Composite materials with different content of aluminum and dispersed additives is obtained: 45Al-44Ti-11C (%, wt.), 50Al-40Ti-10C (%, wt.), 55Al-36Ti-9C (%, wt.), 60Al-32Ti-8C (%, wt.), as well as samples with excess carbon content 50Al-40Ti-15C, 55Al-36Ti-14C (%, wt.). The composites are produced by thermal synthesis in a vacuum induction heating furnace at a temperature of 950 °C and subjected to hot forging after preheating at 600 °C and holding in furnace for 20 minutes.
Studies have shown that the samples of all compositions are maximally compacted after hot forging. The HRB hardness values range from 59-69,1 (for samples with 45-50 (%, wt.) Al) and up to 73,7-76 (55-60 (%, wt.) Al), which depends from the sample composition. For composites with 55-60 (%, wt.) Al and excess of carbon content the electrical conductivity value is 0,38-0,168 Ohm*mm2/m, and slightly higher values of electrical conductivity have materials with a higher content of TiC – 0,23-0,3 Ohm*mm2/m (for composites with 45-50 (%, wt.) Al). Thus, all samples demonstrated rather high electrical conductivity and low values of resistivity.
The results of tribological studies showed intensive wear of samples without excess carbon in combination with copper due to adhesion of the aluminum matrix and the abradant material. Composites with residual carbon have shown 100 times greater resistance than composites without excess carbon. Also, the results of the research showed that the infiltration of composites with antifriction material prevents the friction pair materials from gripping and accordingly, increases its stability.
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Stepan Kyryliuk |
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H3-OK1649 |
Phase equilibria in the ZrO2–HfO2–Eu2O3 system at 1700°C Yuriy Yurchenko1, Oksana Korniienko1, Sergey Korichev1, Anatoliy Samelyuk1, Marina Zamula1, Larisa Spasonova2 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine, Kiev, Ukraine The progress of technology and industry requires the creation of advanced ceramic materials with improved properties. In this desirable sense, ceramic materials based on zirconium and hafnium dioxides doped by REE oxides are promising for modern materials design. Partially or fully stabilized zirconium dioxide is used as a functional and constructional ceramic due to its unique combination of physical and mechanical characteristics. Undoubtedly, ceramic materials based on these oxides, especially based on zirconates (Ln2Zr2O7) and hafnates (Ln2Hf2O7) are attractive and promising for the production of refractories and nodal components of high-temperature technology, in particular, thermal barrier coatings (TBC), as well as phosphors, lasers, catalysts, oxide-ion conductors, as well as materials for immobilizing radioactive waste, modern dielectric and magnetic materials, etc.
The phase equilibria in the ternary ZrO2–HfO2–Eu2O3 system at 1700°C were studied in the overall concentration range by X-ray diffraction and microstructural analyses. New phase in the ternary system was not revealed at 1700 С. The structure of the boundary binary systems defines the phase equilibria in the ZrО2-HfO2-Eu2O3 system. Solid solutions based on cubic with fluorite-type structure (F) and tetragonal (Т) modifications ZrО2 and monoclinic (B) modification Eu2O3, monoclinic (M) modification HfO2 as well as intermediate phase with pyrochlore type structure Ln2Zr2O7 (Ln2Hf2O7) were determined. The refined lattice parameters of the unit cells and the boundaries of the homogeneity fields for solid solutions were determined. It was found that the isothermal cross-section of the ternary diagram of the ZrO2–HfO2–Eu2O3 system at 1700°C characterized by the formation of one three-phase region (T+M+F), as well as six two-phase regions (two F+Py, B+F, F+T, F+M, T+M).
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Yuriy Yurchenko |
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H3-VS2218 |
Effect of cold isostatic pressing pressure of 300 MPa on transverse rupture strength of sintered WC-3 wt.%Co and WC-15 wt.%Co cemented carbides Gennadiy Akimov1, Ihor Andreev2, Vitalii Sheremet3, Iryna Trosnikova3 1Donetsk institute for physics and engineering named after O.O. Galkin of the National Academy of Sciences of Ukraine, Kyiv, Ukraine WC and Co were used as initial powders in this study. The nominal compositions of the cemented carbides were WC-3wt.%Co and WC-15wt.%Co. The powders were pressed into green compacts under uniaxial pressure of 70 MPa. After uniaxial pressing, cold isostatic pressing of half of the samples of each composition was carried out. Subsequently, all green bodies were sintered. Sintering of WC-3wt.%Co was performed in the Ar atmosphere at temperature of 1500 °C for 1 h. WC-15wt.%Co sintering was carried out in a vacuum furnace at 1370 °C for 1 h. The densities of the sintered WC-Co alloys were measured by the Archimedes method. One surface of each alloy was polished. A type Rockwell hardness and transvers rupture strength were measured. UnCIP-ed WC-3wt.%Co samples exhibited density of 14.6 g/cm3, Rockwell hardness of 91 HRA and TRS of 1090 MPa. CIP-ed WC-3wt.%Co samples exhibited density of 15.2 g/cm3, Rockwell hardness of 92 HRA and TRS of 1420 MPa. UnCIP-ed WC-15wt.%Co samples exhibited density of 13.9 g/cm3, Rockwell hardness of 86.5 HRA and TRS of 2140 MPa. CIP-ed WC-15wt.%Co samples exhibited density of 13.9 g/cm3, Rockwell hardness of 87.5 HRA and TRS of 2410 MPa. Reference values for WC-3wt.%Co density 15-15.3 g/cm3, HRA 89.5, TRS 1180 MPa. For WC-15wt.%Co, density is 13.9-14.4g/cm3, HRA 86.0, TRS 1860 MPa. It was found for the first time that WC-3wt.%Co and WC-15wt.%Co cemented carbides produced using preliminary CIP at a pressure of 300 MPa demonstrate a significant increase in TRS compared to reference data for these alloys. WC-3wt.%Co TRS increased by 30% up to 1420 MPa. WC-15wt.%Co TRS increased by 13% up to 2410 MPa.
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Vitalii Sheremet |
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H3-SY1106 |
Phase equilibria in the binary CeO₂-Nd₂O₃ system at a temperature of 1500°С Serhii Yushkevych1, Oksana Kornienko1, Оlena Olifan1, Olesya Pavlenko1, Anatoliy Sameljuk1, Irina Subota2 1Institute for Problems in Material Science, NAS of Ukraine Today, ceramic materials based on REO are in widely used in the technical and functional materials` creation, due to their physical properties, such as hardness, thermal and chemical stability, high ionic conductivity, the ability to store or release oxygen, strong absorption of UV rays, etc. Phase equilibria in multi component oxide systems are considered the physicochemical basis for the new materials creation with predetermined properties.
In the presented work, for the first time phase equilibria and physicochemical properties of phases formed in the CeO₂–Nd₂O₃ binary system at a temperature of 1500 °C (in the air) in the entire concentration range were researched using powder X-ray diffraction and microstructural analysis. Ce(NO₃)₃×6H₂O and Nd₂O₃ with an amount of the main component of 99.99% were used as primary materials. The samples were prepared with a concentration step of 2.5-5 mol.%. X-ray diffraction analysis (XRD) of the samples was performed by the powder method on the DRON-3 device at room temperature (CuКa-irradiation, Ni - filter). The scanning step was 0.05-0.1 degrees, the exposure was 4 sec. in the 2q angles range from 10° to 100°.
The research of the solid-phase interaction of CeO₂ (fluorite type, F, space group Fm3m) and Nd₂O₃ (hexagonal A modification of oxides of rare earth elements, space group P3m1) at a temperature of 1500 °C showed that three types of solid solutions are formed in the CeO₂–Nd₂O₃ system: based on hexagonal modification A-Nd₂O₃, on cubic modification C-Ln₂O₃ and on fluorite-type cubic structure F-CeO₂, which are separated by two-phase fields (A+C) and (C+F), respectively. The F-CeO₂ unit cell parameters vary from a=0.541 nm for pure CeO₂ to a=0.548 nm for a two-phase sample (F+C) containing 70 mol.% CeO₂ – 30mol.% Nd(U+2082)O(U+2083) at 1500°C temperature.
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Serhii Yushkevych |
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H3-VS1921 |
Destruction of spacecraft polymer films under exposure to high-velocity atomic oxygen flows Valentin Shuvalov, Nikolai Gorev, Galina Kochubei, Yuri Kuchugurnyi, Nikolai Pismennyi, Nikolai Tokmak Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine Polymers are widely used in spacecraft as structural materials: outer coatings, structural components of blanket thermal insulation, solar array coverings, etc. In near-Earth orbits (200 km – 700 km), polymer exposure to high-velocity atomic/molecular plasma flows – 5 eV atoms and atomic ions – results in polymer surface sputtering and degradation. In spacecraft designing, materials are selected on the basis of their resistance to long-term exposure to the near-satellite environment, in particular to atomic oxygen (AO) flows, determined from the results of life tests on dedicated setups and material exposure onboard spacecraft.
The goal of this work is to substantiate a methodology and develop procedures for accelerated life tests of polymer films for resistance to long-term exposure to high-velocity AO flows. Experiments were conducted on the ITM plasmaelectrodynamic setup, which has the status of the National Heritage of Ukraine. Polymer samples were exposed to an AO plasma beam followed by the determination of the mass loss and the film surface profile and erosion depth. Surface destruction was studied using an optical microscope and a scanning atomіc-force one.
The polymer sputtering yields, surface roughness, erosion depth, and solar absorptance are determined as a function of the AO fluence over a wide range of the AO ion energy (5 eV – 264 eV) and fluence (1016 ionO/cm2 – 1021 ionO/cm2) using the results of satellite tests in the Earth’s ionosphere and laboratory tests. A methodology is substantiated and procedures are developed for accelerated life tests of polymer films for resistance to long-term AO ion exposure on dedicated setups using 5 to 100 eV AO ions. The life test time acceleration factor is determined as a function of the AO ion fluence and energy using Kapton-H polyimide as the reference material.
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Valentin Shuvalov |
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H3-OB2208 |
Cermet powders based on TiAl intermetallide for thermal spraying Oleksii Burlachenko1, Nataliia Vigilianska1, Cezary Senderowski2 1E.O. Paton Electric Welding Institute, Ukraine Titanium aluminides alloys are widely used in industries but low mechanical properties at room temperature and insufficient resistance to oxidation at temperatures above 800 0 C limits their practical application. Thermal spray (TS) technologies make it possible to produce cermet coatings on the surface of parts, which combine the high specific strength of the metal matrix with the wear
resistance and high-temperature resistance of ceramic inclusions. The aim of this work was to develop the compositions and technology for producing cermet powders based on TiAl with the addition of non-metallic refractory compounds for TS coatings.
The technology of mechanochemical synthesis (MCS) was used to produce cermet powders for TS. TiAl intermetallic powder and powders of carbides (В 4 С,
SiС) and nitrides (ВN, Si 3 N 4 ) were used as starting materials. The choice of the composition of powders was made on the basis of thermodynamic analysis with an
estimation of the possibility of reactions proceeding by the mechanism of mechanically induced self-propagating synthesis (MSS). The study of the produced
powders was carried out using scanning electron microscopy and X-ray diffraction phase analysis. It was found that among the selected compositions of cermet powders, the
passage of MSS during MCS is possible only in 73TiAl+27B 4 C and 69TiAl+31BN compositions, and in the case of 88TiAl+12SiC and 83TiAl+17Si 3 N 4 compositions,
the passage of MSS is impossible. Produced powders in addition to the initial components includes refractory compounds of aluminum (AlB 2 and AlN) and titanium (TiB 2 , TiC, TiN and Ti 5 Si 3 ).
The formation of double carbide Ti 3 AlC was found in TiAl-B 4 C and TiAl-SiC powders. Due to the high degree of dispersion, produced powders do not have
fluidity - one of the main factors that ensures uniform feed of the powder into the high-temperature jet. The technology of their conglomeration with subsequent
sifting of particles with a size of 40-80 microns has been worked out.
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Oleksii Burlachenko |
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H3-ND1042 |
Study of the influence of titanium modification with carbon-containing powder master alloys on tribological properties Nadiya Davydchuk, Mykola Gadzyra, Yaroslav Tymoshenko, Mykyta Pinchuk Frantsevich Institute for Problems of Materials Science, NAS of Ukraine The objective of this research effort is to achieve high characteristics of hardness and wear resistance of sintered titanium powder due to modification with carbon-containing powder composites (master alloys). To obtain the master alloys used synthesized nanosized carbides of silicon, titanium, tungsten and chromium, as well as aluminum powders in a ratio of 1:1. The study of the phase composition of the obtained powder master alloys showed that when heated to a temperature of 900 °C, the interaction of the components in the 50 SiC–50 Al, 50 TiC–50 Al, 50 WC–50 Al and 50 Cr7С3–50 Al wt.% systems occurs with the formation of carbide (SiC), intermetallides (TiAl, Al5W, Al12W, Al8Cr5), ternary compounds of the MAX phases (Al14SiC4, Ti4AlC3, Cr2AlC), as well as carbon of the "skeletal" type. Analysis of the microstructure showed that highly dispersed particles (<5 μm) prevail in powder master alloys. The sintering of the modified titanium hydride powder was carried out at a temperature of 1350 °C in a vacuum for 60 minutes. Analysis of electron microscopic studies of sintered titanium composites with 10 wt.% master alloys showed that all formed samples are characterized by the manifestation of a eutectic structure, the common feature of which is its high dispersion. The analysis of hardness and abrasive wear showed that the wear resistance of sintered powder composites is weakly dependent on the phase composition of the master alloys. The hardness and abrasive wear of the samples were 4.6–5.7 GPa and 51.1–59.6 mg/km. However, better characteristics are achieved when modifying titanium with a master alloy formed in the 50 Cr7C3–50 Al wt.% system and has a hardness of HV5.0=4.7 GPa and an abrasive wear of 51.1 mg/km, which significantly exceeds the wear resistance of the grade VT22 titanium alloy.
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Nadiya Davydchuk |
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H3-YT1808 |
Isothermal section of the Al2O3–TiO2–La2O3 phase diagram at 1400 °С Yana Tyshchenko, Sergij Lakiza, Victor Redko, Elena Dudnik Frantsevich Institute for Problems of Materials Science, Ukraine Phase diagram of the Al2O3–TiO2–La2O3 system is a promising basis for the creation of multicomponent composite materials with a combination of different strengthening mechanisms. In the Al2O3–TiO2–La2O3 system, there are binary compounds with promising dielectric, piezoelectric, and ferroelectric properties.
Isothermal section of the Al2O3–TiO2–La2O3 phase diagram at 1400 °C is constructed for the first time. The 1400°C was taken as the temperature, at which no liquid is expected in the system. Samples were prepared by a chemical method. Samples were annealed in air at 1400°С for 80 hour sand cooled in the furnace. Phases in the samples were determined by XRD analysis. New phases and appreciable homogeneity regions based on components and binary compounds were not found. Isothermal section consists of six narrow two-phase and seven three-phase regions. Triangulation of the system is determined by the phase La2Ti2O7, which is in equilibrium with compounds Al2TiO5, LaAlO3 and system components TiO2 and Al2O3. Formation of phases La4Ti9O24, La2Ti3O12 and La2TiO5 in binary boundary system TiO2–La2O3 causes the appearance of partially quasibinary sections Al2TiO5–La4Ti9O24, Al2TiO5–La2Ti3O12 and LaAlO3–La2TiO5. The obtained results make a significant contribution to the understanding of interactions between the components in the system studied. The system includesbinary compounds with high electro-optical, ferroelectric, piezoelectric, photocatalytic properties,microwave dielectric ceramic. In addition, in the system we expects the existence of new three-phase and two-phase eutectics, which can be obtained in the form of high-temperature structural materials by the directional solidification. This fact opens up the possibility to find and establish the coordinates of new three-phase and two-phase eutectics for directional solidification and to obtain new high-temperature structural ceramics in the Al2O3–TiO2–La2O3 system.
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Yana Tyshchenko |
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H3-HI1213 |
Increasing the efficiency of separation by surface imperfection of low-strength diamond powders Halyna Ilnytska, Olga Loginova, Valerii Lavrinenko, Volodymyr Smokvyna, Iryna Zaitseva Bakul Institute for Superhard materials, National Academy of Science of Ukraine Diamond powders of low-strength grades AC6–AC20 are widely used in tool production in the processing of hard alloys, ceramics, glass, and other brittle materials. Improving the strength
characteristics of diamond powders is one of the most important ways to achieve a higher class of machined surface and increase the wear resistance of diamond tools.
The Institute of Superhard Materials has developed a method for separating diamond powders according to their surface imperfection, which involves preliminary adhesive applicate in air on
defective areas of the surface of grains of metal particles, which ensure their subsequent distribution in a force field into groups with different levels of surface imperfection and strength. As such
particles, magnetic or electrically conductive metal particles are used, and the distribution of grains is carried out in a magnetic or electric field. To ensure a higher selectivity of the fixing of deposited
particles on diamond grains with a developed defective surface, the process can be carried out by adsorption from solutions.
To compare the effectiveness of different deposition methods in this work, the study was carried out on powders of diamond grade AC6 with a grain size of 200/160. Ferromagnetic particles
of iron no larger than 1000 nm in size were adhesive applicate powders in air and water, the particle concentration was 0.5 - 5%. Then, the separation of the diamond powder with iron particles was
carried out in a magnetic field at a strength of 5 to 20 A/m to obtain four fraction of separation. For each batch, the surface imperfection was determined in the form of a surface activity coefficient
(Ka) in % and a strength index in static fracture in N. As a result of separation of the initial powder with a strength of 12.9 N in an aqueous medium, diamond powders were obtained more than 50%
of diamond powders with a strength equal to or higher than 15.0 N were obtained in an aqueous medium, which corresponds to the brand AC15.
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Halyna Ilnytska |
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H3-VK1806 |
Structure and properties of (Ti, Cr)B2–SiC composite materials Volodymyr Konoval, Oleksandr Umanskyi, Iryna Martsenyuk, Konstyantyn Gal'tsov, Oleksii Bondarenko, Viktoriia Chernatska, Serhii Karpenko Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Titanium-chromium boride has high hardness, wear- and heat-resistance. However, high fragility significantly limits its use in a pure form. The introduction of various additives, both metallic and ceramic, makes it possible to obtain new composite materials with higher mechanical and tribotechnical properties [1]. Silicon carbide is such a promising additive. Composite materials with different ratios (Ti, Cr)B2 and SiC (5–30% vol.) were obtained by hot pressing method from a specially prepared powder mixture. The (Ti, Cr)B2-SiC composite materials the composition and microstructure by the scanning electron microscopy (SEM), hardness by the Vickers, strength by the three-point flexure test, wear resistance under of dry friction-sliding conditions methods were studied. The (Ti, Cr)B2-SiC have a heterophase finely dispersed microstructure with a uniform distribution of SiC grains in the bulk of the material. The chemical composition of each of the constituent phases is close to the original. The SiC addition introduction (up to 10% vol.) of in (Ti, Cr)B2 increases the density of the material up to 98% and the flexural strength up to 480 MPa. The hardness decreases linearly in the range HV33–29 GPa. A further increase of the SiC content leads to a low decrease of the density and strength of the material. The wear resistance of the material reaches its maximum values at a content of SiC 5–10% vol. With a further increase of the SiC content the wear resistance depends on the load. The (Ti,Cr)B2–SiC composite materials have higher density, strength and wear resistance compared to (Ti,Cr)B2. An increase in heat resistance is also expected. This allows to significantly expanding the scope of its application. The (Ti, Cr)B2-SiC composite materials are planned to be used as a wear-resistant component of cermet materials for applying gas thermal coatings.
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Volodymyr Konoval |
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H3-AS2003 |
A CaTiO₃ perovskite - TiO₂ rutile composite doped with Nb Anatoliy Smolar, Anatoliy Burkhan, Alexander Bloschanevich, Anatoliy Stegniy, Valeriy Bekenev, Artur Stepanenko, Volodymyr Khomenko, Oleksandr Vasiliev Frantsevich Institute for Problems of Materials Science NAS of Ukraine Application of materials with perovskite structure has become one of the most promising approaches to the development of photovoltaic systems. Optimization of perovskite-like materials, conventionally called perovskites, and devices based on them allowed to increase the efficiency of harvesting solar light into electricity from around 3% to almost 30% in just under ten years. The majority of current solutions use metal halide compounds with organic or heavy metal cations, which suffer from low thermal and chemical stability, have short service life, pose environmental threats. The CaTiO₃ perovskite does not have the mentioned drawbacks and its performance in solar cells can be significantly improved by doping, particularly with Nb. In this work, electronic density of states of Nb-doped CaTiO₃ was calculated with the Density Functional Theory and virtual crystal approximation showing an increase in the amount of charge carriers with Nb concentration. A CaTiO₃ perovskite - TiO₂ rutile composite was produced by the rapid furnace synthesis with concurrent heavy doping of the product. Further X-ray diffraction analysis showed the formation of Ca(Ti, Nb)O₃ solid solution and specific resistivity of the composite sample was measured to be ~0.7 Ω·m, in contrast to typical values of ~10⁹ Ω·m for CaTiO₃ perovskite. While specific reasons for the difference still require clarification, the Nb doped composite is worth exploring for application in photovoltaic systems.
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Artur Stepanenko |
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H3-VP1422 |
Microstructure and physico-mechanical properties of titanium-based porous composites for anode substrates of solid oxide fuel cells Viktoriya Podhurska1, Dmytro Brodnikovskyi2, Mykola Gadzyra2, Bogdan Vasyliv1, Yehor Brodnikovskyi2, Orest Ostash1, Oleksandr Vasylyev2, Bora Timurkutluk3 1Karpenko Physico-Mechanical Institute of NASU, Ukraine In this work, the microstructure and physico-mechanical properties of the candidate solid oxide fuel cell anode materials of the Ti–SiC (material 1 with 30% porosity) and TiC–AlON (material 2 with 35% porosity) systems were investigated in the initial state and after holding at 600°C in air or hydrogen. Scanning electron microscopy analysis revealed that the phase composition of material 1 presents titanium carbide TiC and titanium silicide $Ti_{5}Si_{3}$, whereas material 2 presents titanium carbide TiC, aluminum oxynitride AlON and alumina $Al_{2}O_{3}$. It was found that in the initial state flexural strength of materials 1 and 2 is 105 MPa and 110 MPa, respectively, whereas their electrical conductivity is $3.81\cdot 10^{5}$ S/m and $4.88\cdot 10^{5}$ S/m, respectively. At the same time, material 1 is fractured mainly by transgranular cleavage, and material 2 is fractured by transgranular cleavage with some elements of intergranular cleavage.
At 600°C and holding for 3 hours in the air, the studied physico-mechanical characteristics of material 1 are 71 MPa and $3.05\cdot 10^{5}$ S/m, while the fracture micromechanism remains the same. The corresponding characteristics of material 2 are 140 MPa and $4.88\cdot 10^{5}$ S/m at the predominance of intergranular fracture of the TiC phase and microductile fracture of aluminum oxynitride AlON. At 600°C and holding for 3 hours in hydrogen, these characteristics of material 1 are 41 MPa and $3.39\cdot 10^{5}$ S/m at significant changes in the fracture micromechanism with the appearance of a large number of intergranular secondary microcracks. For material 2, they are 80 MPa and $4.88\cdot 10^{5}$ S/m at the predominance of intergranular fracture.
Based on the obtained results, it was established that both investigated materials have a high level of electrical conductivity under different test conditions, but in terms of mechanical properties, the composite of the TiC–AlON system has an advantage over the composite of the Ti–SiC system.
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Viktoriya Podhurska |
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H3-LC0001 |
Composite h-BN–magnetite nanopowders for cancer therapy application Levan Chkhartishvili1,2, Shio Makatsaria1,3, Otar Tsagareishvili2, Shalva Kekutia1, Jano Markhulia1, Vladimer Mikelashvili1, Natia Barbakadze4, Maia Japaridze4, Roin Chedia2,4 1Georgian Technical University Using a chemical synthesis method from liquid charge [1,2], the hexagonal boron nitride h-BN matrix magnetic nanopowder composites are obtained by coating or intercalation of h-BN nanoparticles with ferrimagnetic iron oxide Fe3O4 (magnetite). VSM (Vibrating-Sample-Magnification) studying [3] of the room-temperature magnetization curves confirms their potential to serve for neutron-capturing boron isotope 10B effective delivery agents in BNCT (Boron-Neutron-Capture-Therapy) of cancer as BN–magnetite composite nanoparticles allow the controlling by an external magnetic field to target them to tumor tissue.
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Levan Chkhartishvili |
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H3-YS2324 |
Formation and properties of layered Ti-TiB/Al composite material Yana Smirnova, Iryna Huriia, Petro Loboda National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” Layered Ti/Al composite materials have a range of unique properties, which makes them promising for automotive, aerospace, defense and other industries. The aim of this work was obtaining and experimental study of layered Ti/Al composite. For producing of layered composite material were used 1,4 mm thick titanium plates reinforced with titanium boride (Ti-TiB). A flux based on the KF-AlF3 eutectic system was applied on polished and cleaned inner surface of the plates. Two Ti-TiB flux coated plates assembled into a package, infiltrated and held in molten commercial pure aluminium at a temperature of 700 °C for 300 s. The width of the gap between the plates varied from 0,5 to 1,5 mm. Obtained composites was studied using SEM, EDS and XRD methods. Formation of the transition layer in interaction zone between solid Ti-TiB and liquid Al is observed for all samples. The transition layer thickness is stable for all values of the width of the gap between the plates and amounts to an average of 6,3±0,27 – 6,5±0,28 μm. The concentration of elements in the transition layer according to the stoichiometric composition corresponds to the phases TiAl3, TiAl2, TiAl and the solid solution of titanium in aluminum. Titanium boride fibers are present in the transition layer and some of them transferred into the aluminum part as a result of plate interaction with the melt. According to the XRD of the interaction zone there are only titanium, titanium borides and aluminum in the transition layer. It can be assumed that the amount of intermetallic phases that can form in the transition layer is too small to be identified by XRD. Composites with the gap of 1,5 mm were investigated by uniaxial tensile test. It was established that the tensile strength of the three-layer Ti-TiB/Al composite is 479±18 MPa on average, and the deformation is 14,96±1,7%. Fractographic studies demonstrate that tensile failure of samples does not lead to complete delamination of the material.
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Yana Smirnova |
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H3-IM1217 |
Influence of the composition of a ZrO2-based solid solution on low-temperature phase stability system materials ZrO2–Y2O3–CeO2 Irina Marek1, Olena Dudnik1, Vasilij Vynar2, Viktor Redko1, Oleksij Ruban1 1Institute of Problems of Materials Science NAS of Ukraine The problem when using ZrO2-based ceramics is the aging process, which occurs through a gradual uncontrolled martensitic type T-ZrO2→M-ZrO2 phase transformation on the ceramic surface. Aging leads to surface roughness and destruction of ceramic implants used in medicine.
The ZrO2–Y2O3–CeO2 system opens up wide possibilities for optimizing the strength, toughness, and phase stability of ceramics. The materials of this system combine the high strength of Y-TZP with the high critical fracture toughness coefficient (К1с) and aging resistance of Ce-TZP. The combined stabilization of ZrO2 allows to achieve an increased level of materials mechanical properties and to improve their low-temperature phase stability.The purpose of the work is to investigate the low-temperature phase stability of the materials in the ZrO2–Y2O3–CeO2 system at different ratios of yttrium and cerium oxides in the ZrO2-based solid solutions.
The compositions of the materials in the ZrO2–Y2O3–CeO2 system, % (mol.): 97 ZrO2–3 Y2O3 →Zr (3Y); 95 ZrO2–3 Y2O3–2 CeO2 →Zr (3Y2Се); 92,5 ZrO2–2,5 Y2O3–5 CeO2 → Zr (2,5Y5Се); 90 ZrO2–2 Y2O3–8 CeO2 → Zr (2Y8Се); 88 ZrO2–12 CeO2 →Zr (12Се) were selected for investigations.
Investigation of resistance to low-temperature degradation ("aging") of the obtained powders heat-treated under different conditions was carried out. The preservation of 100% T-ZrO2 in composites with the composition (mol%): 90ZrO2–2Y2O3–8CeO2 and 88ZrO2–2CeO2 was established, which indicates their increased resistance to aging. It was established that the optimal temperature for heat treatment of the initial powders is 850℃. So it was determined that powders with the composition (mol %): 90ZrO2–2Y2O3–8CeO2 and 88ZrO2–2CeO2 are promising for the creation of ceramic bioinert implants for various purposes.
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Irina Marek |
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H3-BP1227 |
Percolation simulation for conductor/insulator materials during SPS considering porosity Bohdan Pokhylko, Vladyslav Kushnir, Andrey Ragulya Institute for Problems in Materials Science NAS of Ukraine The main feature of Spark Plasma Sintering (SPS) is Joule heating by passing an electric current through a sample and/or graphite die. Conductive samples can be heated from the “inside” which can affect the densification process. Especially it is important for materials of conductor/insulator system (C/I) which can turn from an insulator into a conductor during SPS. The powder C/I sample actually consists of two insulating phases: the insulator and the porosity reducing during sintering. And conductivity of the C/I drastically increases at a certain content of the insulating phases, the so-called percolation threshold. It happens due to the formation of percolation clusters of conductive particles. That means that the temperature distribution, and accordingly densification process, during SPS can be drastically changed leading to unwanted consequences like inhomogeneous microstructure. Most of the related works do not consider porosity and complex particle shape [1]. Therefore, the main task of this work is to understand how current flows through the porous C/I sample during SPS.
A model based on cellular automaton was developed. Two types of 3D meshes were built: simple – particle is a separate cell; complex – particle is a set of cells representing a particle shape. For check for percolation of the simple model, the following numbers of adjacent cells to which the current can pass were set: 6, 8, 12, 18 and 26 due to the conductivity is directly related to the number of interparticle contacts.
Contradictory of the percolation threshold calculated by known equations and our model was discovered – 33 against 15% (content of conductive phase) respectively. 33% corresponds to the simple model with only 6 interparticle contacts while the complex model mostly shows ~15. More advanced equations need to be developed. The number of interparticle contacts to achieve the percolation must be ~11. At the start and end of the simulation it equals ~8 and ~15 respectively.
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Bohdan Pokhylko |
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H3-ОК1240 |
Hydrogen generation by hydrolysis of MgH2 – Ti-based IMC – C composites Vasyl Berezovets, Oleksandr Kononiuk, Ihor Zavaliy, Andriy Kytsya, Ihor Borukh Karpenko Physico-Mechanical Institute of the NAS of Ukraine Magnesium hydride MgH2 and its composites are promising materials for hydrogen storage [1]. Another promising direction of using MgH2 is generation of hydrogen by hydrolysis. An obstacle to effective hydrolysis of MgH2 is the formation of a compact layer of magnesium hydroxide on the surface of the reacting material. To solve this problem, the magnesium with catalytic additives are ball milled, and compositions of the solutions used for hydrolysis are modified. The addition of Ti-based intermetallic compounds (IMC) accelerates the synthesis of magnesium hydride in many times [2]. Use of salt solutions in the hydrolysis increases the conversion rate and the speed of hydrogen release [3]. In this work, the influence of graphite additives and Ti-based IMC on the hydrolysis properties of magnesium hydride was investigated. Composites were obtained by reactive ball milling in hydrogen. The starting components were magnesium shavings, graphite powder, and arc-melted and annealed TiFe and Ti3Fe3O compounds. Hydrogen sorption was studied using a Sieverts-type apparatus. X-ray phase analysis was performed on a powder X-ray diffractometer DRON-3.0 (Cu-Kα radiation). The kinetics of MgH2 hydrolysis was studied under pseudoisothermal conditions. Amount of released hydrogen was measured by the volumetric method. Mechanochemical synthesis of MgH2–IMC–C composites and their hydrolysis in deionized water and MgCl2 solution of different concentrations were carried out. It has been shown that the addition of graphite leads to a greater grinding of the powder and improves the conversion rate by 10-20%. The logarithmic dependence of the degree of conversion on the composition of the solution is shown. Thus, increasing the concentration of MgCl2 from 0.05 to 0.1 mol/L leads to an increase in conversion rate by only 6%. The effect of additives on the degree of conversion during hydrogen generation by hydrolysis was analyzed.
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Oleksandr Kononiuk |
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H3-KV1342 |
New composite materials for negative electrodes of Ni-MH batteries Khrystyna Vlad, Yuriy Verbovytskyy, Ihor Zavaliy, Yuriy Dubov Karpenko Physico-Mechanical Institute of the NAS of Ukraine Bimetallic nanoparticles have attracted considerable attention as catalytic materials for different chemical reactions, including hydrogen generation by hydrolysis of NaBH4 [1]. In recent years, many efforts have been made also to find new materials suitable for effective electrochemical power sources. We supposed that Ni-based nanoparticles [2,3] due to their high surface area, electrical conductivity, chemical stability and low cost could be used as effective additives to materials of the negative electrodes for nickel-metal hydride (Ni-MH) batteries. This kind of chemical power sources have many advantages, such as high discharge capacity, resistance to overloads, absence of toxic metals, etc. In this work he results of the study of electrochemical properties and charge-discharge parameters of new composite materials will be presented. Intermetallics of A2B7 and A5B19 compositions (A=RE, Mg; B=Ni, Co) were synthesized by arc melting and sintering. Phase-structural analysis was carried out using X-ray powder diffraction. Ni-Co-based nanopowders for additives were synthesized by leaching from the corresponding aluminides. The composition and morphology of the powders were studied by SEM/EDS methods. An experiment on cyclic durability (periodic electrochemical charge/discharge) was used to find out the use of certain composites as negative electrodes for Ni-MH batteries. Ni-Co nanopowders were used to modify electrodes in order to increase the kinetics of charge/discharge processes and operational parameters. Their electrochemical properties were studied previously by chronoamperic and voltamperic methods. The obtained materials were characterised by high discharge capacity (more than 400 mAh/g) and cycle life (more than 90% after 50 cycles).
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Khrystyna Vlad |
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H3-DB1535 |
The influence of chemical-thermal treatment on the chemical composition and stability of the mechanical and electrical properties of the composite material based on Ti-Si-C Dmytro Brodnikovskyi1, Viktoria Podhurska2, Yaroslav Tymoshenko1, Serhy Tkachenko3, Oleksander Myslyvchenko1, Mykyta Pinchuk1, Ladislav Čelko4, Bora Timurkutluk5, Orest Ostash2, Oleksander Vasylyev1, Bogdan Vasyliv2, Ihor Polishko1, Natalia Lysunenko1, Yegor Brodnikovskyi1, Mykola Gadzyra1 1Frantsevich Institute for Problems of Materials Science of NASU, Ukraine
A titanium-supported Solid Oxide Fuel Cell (SOFC) is a promising alternative to a steel-supported one desirable for unmanned aerial, marine or space vehicles, and other portable wearable applications like soldier ammunition, oxygen concentrators for medical patients etc. The studies performed by authors confirm that Ti-MAX phases and Ti-Si-based nanocomposites can be used as light-weight alternatives to high temperature iron-base materials in SOFC systems.
The advanced Ti-based materials were elaborated and studied for their phase composition, microstructure, mechanical behaviour, and electrical conductivity before and after thermochemical treatment simulated solid oxide fuel cell (SOFC) operation conditions. The data generated by the project partners showed that the sintered materials based on Ti-MAX-phases and titanium composites are promising candidates for application as lightweight interconnect alternatives to high Cr steels (e.g., Crofer 22 APU). Ti-MAX-based materials are almost twice lighter (~4.5 g/cm3) than Fe-based interconnects [1, 2]. The MAX-phases exhibit unique properties combining the merits of metals and ceramics, such as high thermal and electrical conductivity, high strength and modulus, damage tolerance and thermal shock resistance, and, more importantly, machinability that permits the removal of the material with a satisfactory finish at low cost.
Ti-Si-C based materials would allow to completely escape from the chromium poisoning problem during SOFC operation thereby enhance SOFC stack life time and facilitate developing of commercial attractive light-weight SOFC stacks for mobile systems.
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Dmytro Brodnikovskyi |
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H3-TK2132 |
Solid solutions of aluminum in boron carbide as means to modify its mechanical properties Valerii Muratov, Oleksandr Vasiliev, Viktor Garbuz, Petro Mazur, Tetyana Khomko Frantsevich Institute for Problems of Materials Science NAS of Ukraine Boron carbide is an important superhard material for extreme conditions, from specialized industrial articles to ballistic protection plates. Its further application is limited by low fracture toughness (1.5-2 MPa·m$^\frac{1}{2}$) and high temperatures of hot-pressing (above 2100℃). The aim of this work was to modify the boron carbide structure by aluminum to form a solid solution and study the resulting influence on the hardness and fracture toughness of the material. Thermodynamic analysis of reactions in the B₄C-Al system shows that interaction is possible only with gaseous Al. To create the required conditions, the synthesis was carried out in a vacuum at 1400℃ for one hour. X-ray diffraction studies of the product with excess Al in the reacting mixture shows that initial B₄C with a = 0.56022 nm, c = 1.20883 nm completely transformed into a new phase with a = 0.56739 nm and c = 1.24669 nm. The minor differences of lattice parameters suggest that the framework of icosahedral boron was preserved and intericosahedral chains CCC or CBC were modified instead. As atoms on the chain edges are strongly bonded go the icosahedra, we can assume that Al substitutes the middle atom in the chain forming the solid solution. The product also contains ternary compounds Al₃BC and Al₃BC₃, thus Al substitutes both carbon and boron. The former phase hydrolyses in air and had to be removed by chemical methods, and the final composition of the product was 85 mass% B₁₂(CAlC) and 15 mass% Al₃BC₃. The latter carboboride is not icosahedral, has a melting temperature around 1700℃ and allowed to lower the temperature of hot pressing of the system to 1820-1840℃. The Vickers hardness of the composite ceramics was measured to be 20GPa and fracture toughness by indentation was up to 4.5 MPa·m$^\frac{1}{2}$. Thus, the material shows clear technological and service properties advantages in comparison with pure boron carbide.
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Valerii Muratov |
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H3-PS2347 |
CVD synthesis and morphology of TiC micro- and nanofibers Peter Sylenko, Alex Pokropivny, Denis Andrushchenko, Mykola Yakubiv, Igor Okun, Yuriy Solonin Frantsevich Institute for Problems of Materials Science of NASU, Kyiv, Ukraine Method of chemical vapor deposition (CVD) was found to be very perspective for synthesis of carbides [1,2] and nitrides [3-5]. In this study synthesis processes of TiC micro- and nanofibers by the method of CVD were considered. The investigation of synthesized structures by scanning electron microscopy had shown that the use of TiCl4 and C7H8 or CCl4 as reagents and Fe, Co, Ni and Al as catalysts allow the production of TiC micro and nano fibers that could be used to create titanium-based fiber composites. The mace-like structure for the first time was grown on a Ni particle of the metal catalyst, which was absorbed and transferred to the microfiber during growth by the steam-vapor-crystal mechanism. Among the TiC precipitate, synthesized using Co micropowder as a catalyst, nanofibers with elongated balls, i.e., a necklace similar to a nanostructure, were found. Similar to that nanostructures were obtained after annealing SiC/SiO2 nanocables. The reason for their occurrence could be the oscillation of the parameters of the steam-gas mixture during synthesis, which has already been experimentally investigated many times.
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Alex Pokropivny |
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H3-SV1058 |
Thermal stability of powdered TiN and mixtures BaO-TiN(1:1) Dmytro Mishchenko E.O. Paton Institute of electric welding National Academy of Sciences of Ukraine In recent years, wick (oxide) electrodes have been developed and improved for welding materials and products, the inserts for which are formed, mainly, from refractory powders.In this work, the phase transformations that occur in powdered TiN and BaO-TiN(1:1) mixture on derivatograph during heating in air at 15–20 K/min were investigated. in the range of 20-1000-1500°С. in corundum crucibles. The purity of all materials was 99%. There are no data on the heat resistance of TiN powders and mixtures of the BaO-TiN system. At the first stage, oxidation of TiN powder in air was investigated. It was established that slow oxidation of TiN begins at 100°C, which is accompanied by mass growth and heat release. This is not surprising, because during the heating process, most likely, a reaction occurs with the formation of titanium oxonitride: 2TiN+O2 →2TiON first on the surface, and then in the volume of the powder. It is clear that in this process one oxygen atom is rooted in the interstitial space of the TiN solid solution. This causes an increase in the mass of the sample. At the same time, a small increase in T is observed and a small amount of heat is released. From 400 to 920°С, the mass of the sample begins to decrease, and T increases quite significantly. This may be due to the decomposition of titanium oxonitride, which can be represented by the following equation: 2TiON→2TiO2+N2.. State diagrams of the BaO-TiN system have not been constructed. According to the resulting derivative diagram of the powdery mixture of the BaO-TiN system in a ratio of 1:1, the following processes take place: 1. decomposition of Ba(OH)2·8H2O, and then Ba(OH)2 at (100-420°С); 2. oxidation of TiN (300-420°С); 3. decomposition of BaCO3 (900-1120°С). The temperature intervals at which these substances decompose are slightly different from the literature data [1], which were obtained under equilibrium conditions, and not when the sample was heated at a constant rate of 15 K/min.
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Dmytro Mishchenko |
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H3-AR7270 |
The impact of heating rates on the MAX-phase Ti3AlC2 formation Inna Kirian1, Alexander Rud2, Andrey Lakhnik2 1G. V. Kurdyumov Institute for Metal Physics of N.A.S. of Ukraine Materials with unique physico-mechanical properties garnered significant attention in materials science. One such class of materials is the recently discovered layered ternary nitrides/carbides known as MAX-phases. MAX-phases possess a unique blend of metallic and ceramic properties. The current investigation represented a novel methodology devised for the pressureless synthesis of the high-purity MAX phase. This method is featured by the short time in duration. The powder blend was prepared from elemental powders of Ti, Al, and spectrally pure graphite. The powders were mixed in an atomic ratio of 3:1.1:2, with an additional inclusion of 5 wt. % boron oxide (B 2 O 3 ). The homogenization of the mixture was carried out at room temperature for a duration of 1 hour using a high-energy laboratory planetary mill (Fritsch Pulverisette P-6). Then compressed pellets were sintered at different temperatures and heating rates in an argon atmosphere. The processes of phase formation during mechanical activation of the initial powders and the structural parameters of individual phases have been studied by X-ray diffraction analysis.
The formation of the Ti 3 AlC 2 MAX phase in the Ti 3 Al 1.1 C 2 + 5 wt.% B 2 O 3 sample was observed to occur at approximately 1435 ºC, employing a heating rate of 40 K/min. However, the MAX phase amount in the sample is not above 70 wt.%. After heating the sample at a rate of 100 K/min, the proportion of the Ti 3 AlC 2 phase increased significantly, reaching approximately 88 wt.%. In
addition, about 12 wt% TiC was also observed in this sample. The optimal outcome was achieved by further enhancing the heating rate to 120 K/min. Consequently, the synthesized sample exhibited a composition comprising approximately 94 wt.% of the MAX phase Ti 3 AlC 2 and 6 wt.% of the TiC phase. The proposed process employs a high heating rate of approximately 10 2 K/min, which impedes the formation of undesirable phases and reduces elemental loss due to the brief duration of the process.
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Alexander Rud |
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H3-AM1521 |
Features of the formation of solid solutions based on ZrO2 in the presence of complex stabilizer Alina Makudera1, Sergij Lakiza2, Olena Dudnik1, Viktor Red'ko1, Tatiana Babutina1 1Frantsevich Institute for Problems in Materials Science, Ukraine The standard material for the ceramic layer of thermal barrier coatings (TBP) is a ZrO2-based solid solutions, stabilized with (6−8 wt.%) Y2O3 (YSZ). It is approaching the temperature limit of its application (<1200 °C) due to sintering and phase transformation t'-phase ZrO2 → T-ZrO2 + F-ZrO2 with subsequent formation of M-ZrO2. The creation of a new generation of TBP based on a ZrO2 solid solution, complexly doped with REE oxides of the yttrium subgroup (heavy concentrate (HC) is relevant.
The following composition of the mixture was chosen for the study: 90 wt.% M- ZrO2 + 10 wt.% HC. Composition of HC (wt.%): 13.3 Y2O3, 1.22 Tb4O7; 33.2 Dy2O3; 8.9 Ho2O3; 21.8 Er2O3; 1.86 Tm2O3; 12.5 Yb2O3; 0.57 Lu2O3; the total content of other oxides is 6.65 (including 3.2 Al2O3). To determine the influence of the dispersion of the original ZrO2 powder on the mixture phase transformations during heat treatment at 800 °C, two M-ZrO2 powders were used: nanocrystalline hydrothermal powder and industry produced fine-grained powder. The mixtures were prepared by the ceramic method and fired at 800 °C for 2–22 hours. Sampling was carried out every 2 hours. The methods of X-ray phase and microstructural analysis, as well as the BET method, were used to study the properties of the samples.
It was determined that the phase transformation M-ZrO2 → T-ZrO2 is accompanied by an inflection on the direct dependence of the specific surface area of the mixtures on the heat treatment time. It was established that T-ZrO2 in a mixture with hydrothermal M-ZrO2 was formed after 14 hours of exposure, and in a mixture with fine-grained ZrO2 – at 14 hours. Regardless of the exposure time at 800 °C, soft agglomerates of a rounded shape remain in both mixtures.
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Alina Makudera |
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H3-SM8241 |
Oxide spinel protective coatings for steel interconnects of solid oxide cell stacks Sebastian Molin, Justyna Ignaczak, Omid Ekhlasiosgouei, Piotr Jasiński Politechnika Gdańska, Poland Solid oxide cell (SOC) stacks are highly efficient electrochemical energy converters, which have again gained a considerable attention in the last years. One of the applications of SOC stacks is large scale energy storage. To build long-lasting, stable stacks, all the system components need to be optimized. One of the main degradation sources is connected to the use of steel interconnects (bipolar plates), which undergo high-temperture oxidation, resulting in electrical resistance increase as well as possible Cr-species volatilization. In order to prevent these phenomena, ceramic protective coatings are developed. This work will present an overview of the protective coatings researched at Laboratory of Functional Materials at Gdańsk University of Technology. The work comprises design of novel materials, synthesis of powders, optimization of coating procedures as well as corrosion studies, including real stacks.
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Sebastian Molin |
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H3-VZ1348 |
Effect of boron oxide on operational properties of coatings obtained from germanium oxide and zinc sulfide for IR-optics Viktor Zinchenko1, Igor Magunov1, Olga Mozkova2, Boris Gorshtein2 1O.V. Bogatsky Physico-Chemical Institute of National Academy of Sciences of Ukraine Optical devices require the application of special coatings that increase their resolution, contrast, functionality, etc. The most popular are thin-film coatings that work on the principle of light interference. Materials from which interference coatings are made must meet certain requirements. In the case of metal oxides, this is purity with the formation of defect-free coatings with reproducible properties; for metal sulfides and fluorides, the most important are stoichiometry and the absence of oxide admixtures. Most often, the coating is obtained by thermal evaporation in a vacuum. The starting materials (GeO2 and ZnS) were investigated using traditional method for materials. For the first time, the possibility of practical application of GeO as a material for optics in the IR range has been established. However, its use turned out to be impossible without the addition of Boron oxide, B2O3, which acts as a stabilizer of the valence state of Ge(II). This made it possible to successfully replace the traditional material – SiO in large-sized optical elements. GeO in coatings has the exceptionally high climatic resistance. The addition of B2O3 actually catalyzes the reaction between SiO and GeO2, the only volatile product of which is GeO. In a different way, the B2O3 additive works in the case of metal sulfides and fluorides, in which oxide impurities are bound into complex compounds. This makes it possible to reduce their ability to interact with the materials of the evaporator, and therefore to pollute the coating with reaction products. In turn, this has a positive effect on the optical and operational properties of coatings compared to those produced from traditional, unalloyed materials. Thus, the mechanical strength increases by 5-10 times, which brings the coating to the highest category – to group 0. This applies not only to ZnS itself, but also to materials based on it, for example, CVD-composite of ZnS–Ge composition and others.
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Viktor Zinchenko |
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H3-NI1839 |
Features of the formation of ceramic coatings on titanium alloys by plasma-electrolytic treatment with the addition of hydroxyapatite and diatomite Nataliia Imbirovych1, Krzystof Jan Kurdzydlowski2, Oleksandr Povstyanoy1, Valentyna Tkachuk1 1Lutsk National Technical University, Ukraine This work aims at establishing the relationship between the composition of biocompatible coatings and their properties, synthesized in alkaline electrolytes by plasma electrolytic oxidation (PEO).
For better fusion of implants with bone tissue, the morphology of the implant surface have an important role. Therefore, special attention is paid to the porosity of the surface. Recently, the plasma-electrolytic oxidation (PEO) method has been used to obtain ceramic coatings on titanium alloys, including those containing calcium and phosphorus. The advantage of the method is that the obtained coatings on titanium alloys have a highly porous surface, the open porosity of which is up to 0,75%, which determines the speed of implant implantation due to the penetration of soft tissues into the pores. It is known that silicon promotes the activation of bone tissue regeneration. As a result of modification of oxide ceramics with components of the hydroxide group of hydroxyapatite, diatomite, pyrophosphate and polyphosphate, it is possible to obtain coatings characterized by osteoinductivity, biocompatibility and bioactivity.
It was established that the coatings synthesized in the electrolyte without the addition of hydroxyapatite are characterized by the formation large in size, but less commons craters on the surface.
Experimental studies revealed that the introduction of diatomite into the electrolyte leads to the stabilization of the PEO process, as a result of which no jump-like changes in voltage and current were recorded at the beginning and the end of synthesis. It was found that the surface of coatings obtained in electrolytes containing diatomite is characterized by greater roughness and porosity.
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Nataliia Imbirovych |
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H3-OU1126 |
Influence of Ni content on microstructure and microhardness of nickel-graphite abradable seal coatings produced by plasma spraying Oleksandr Umanskyi1, Oleksiy Kuschev1, Maryna Storozhenko1,2, Iryna Martsenyuk1, Oleksandr Terentiev1, Valery Brazhevskyi3, Ruslan Kostyunyk4, Vitalyi Krasovskyy1, Oleksandr Chernyshov3, Tetyana Mosina1 1Frantsevych Institute for Problems of Material Sciences NAS of Ukraine In order to increase the efficiency of gas turbine engines, it is necessary to reduce the gap between turbine casing and blade tips. To achieve this goal, abradable seal coatings are applied on the inner surface of the casing. During the gas turbine operation, the blade tips cut into the coating, providing minimal clearance. These coatings should have low hardness to reduce the wear of blade tips, good bonding strength to prevent spalling off failure, high enough erosion and oxidation resistance. Due to low hardness, self-lubricating properties, and low cost, graphite is considered a promising component to design abradable coatings. However, the deposition of pure graphite on metal substrates is impossible by thermal spraying technique. That is why it is necessary to introduce a metal binding component to provide a high level of adhesion and cohesion of the graphite-based coating. In this study, the graphite-nickel composite powders were developed to deposit abradable coatings by plasma spraying. The particles of such powders consist of a graphite core coated with a Ni layer, which has high heat resistance and can protect graphite from oxidation during plasma spraying. This study aims to investigate the influence of Ni content on the structure and properties of the Ni-C composite powders and plasma coatings. It is shown that nickel-cladded graphite powder with 75 wt.% Ni content (NPG-75) is promising for the thermal spraying of abradable coatings. In this case the thickness of Ni layer on the graphite particles reaches 6-12 µm, the NPG-75 powder has good flowability. The NPG-75 plasma coatings were deposited onto steel substrate. The composition, structure and properties of the coatings were studied.
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Maryna Storozhenko |
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Poster session Important.session is online-only and include 5 min presentation in the common conference room and 1 hour of discussion in individual rooms (Zoom) |
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H3-VI1708 |
Characterization of the Ti-Zr-Mo-C coatings deposited by magnetron sputtering Volodymyr Ivashchenko1,2, Alexei Onoprienko1, Petro Skrynskyy1, Aleksandr Pogrebnjak3,2, Oleksii Sinelnichenko1, Andrii Kovalchenko1, Olena Olifan1, Oleksandr Marchuk1 1Frantsevich Institute for Problems of Materials Sciences, NAS of Ukraine A combination of the unique properties of transition metal carbides (TMC) makes them very promising as protective and wear-resistant coatings for various tools, in particular, the cutting, drilling, and milling machines. One of possible ways to improve the performance of such coatings is an increase of their constituent elements to form multicomponent solid solutions based on TMC. It is a such an approach that was used in the present investigation.
The Ti-Zr-Mo-C coatings were deposited onto Si (100) substrates by direct current magnetron co-sputtering of the Ti0.5Zr0.25Mo0.25 and graphite targets. All the deposition parameters were fixed, beside of the current supplied to the graphite target (IC) that changed in the range of 150-300 mA. The coatings were characterized by using XRD, XPS, indentation, tribological tests. XPS investigations revealed the following bonds in the coatings: Ti-C, Zr-C, Mo-C and C-C and there were no Ti–Ti, Mo-Mo and Zr–Zr bonds. The XRD and XPS data enabled one to suppose that the deposited films consisted of the (Ti,Zr,Mo)C solid solution crystallites embedded into the amorphous carbon matrix, a-C. The Knoop hardness (HK) is an extremal function of IC with the maximum value of about 35 GPa at IC = 250 mA. This value is higher than HK of the constituent binary TMC and can be assigned to the formation of the solid solutions. For the film deposited at IC = 300 mA the friction coefficient was lowest (0.12). The low value of the friction coefficient of this coating can be explained by the rather high carbon content: the graphite layers that surround the crystallites serve as a solid lubricant.
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Volodymyr Ivashchenko |
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H3-AK1749 |
Sputtering of Fe with addition of Mo or W by nitrogen ions: Monte Carlo simulation Anatoly Kuzmichev, Michailo Melnichenko Igor Sikorsky Kiev Polytechnic Institute, Ukraine The ion sputtering is used for coating deposition. The main its characteristic is the dependence of sputtering coefficient on energy of bombarding ions. Unfortunately, data on such characteristic for nitrogen ions are very limited, although nitriding and deposition of nitride layers are widely used in practice. This characteristic is of particular interest to iron alloys because of their practical importance. The purpose of the work is to estimate the coefficients of sputtering with atomic nitrogen ions for compositions containing Fe and Mo or W. The Monte Carlo calculation for ion energies in the range of 0.1–70 keV was performed using the TRIM code, which gives good agreement with experiment. The amorphous target microstructure was assumed. In the indicated above energy range, the sputtering coefficient S for pure Fe is 0.33…0.46 with the maximum value of 1.2 at ion energy of 2 kV. For the composition Fe+1%Mo, the values of the partial coefficient SFe for Fe are 0.25-0.35 and 0.91 at the same ion energies; for Fe+5%Mo, the values of the coefficient SFe are 0.23…0.31 and 0.91; for Fe+1%W, the values of the SFe coefficient are 0.2…0.28 and 0.76; for Fe+5%W, the values of the SFe coefficient are 0.2…0.29 and 0.75, respectively. It can be seen, the heavier and larger the additives to iron, the more SFe is reduced. The decrease in the coefficient SFe is disproportionately stronger than the increase in the relative concentration of heavy additives, both Mo and W. In the case of 1%Mo additive, the partial coefficient of molybdenum SMo is 0.005...0.006 and 0.01, and for 5%Mo we have SMo = 0.01…0.01 and 0.04, respectively. In the case of 1%W addition, the partial coefficient SW is 0.003…0.004 and 0.01 and for 5%W we have SW = 0.008…0.01 and 0.03, respectively.These features, as it may be assumed, are due to strong scattering of relatively light nitrogen ions and recoil iron atoms by heavy Mo and W atoms within the target.
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Anatoly Kuzmichev |
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H3-AD1227 |
Lifetime Improvement of Contact Brush Units of Automotive Power Machines Andrii Dovhal National Aviation University, Ukraine The automotive electric equipment involves the electric machines (starter, alternator) incorporating the brush unit and hybrid drive vehicles as well. It is the friction joint of conducting copper and graphite brush. Work efficiency and lifetime of these machines strongly depend on the contact quality and general state of this friction joint.
Thus preset objective of this study is research of friction joint of brush unit “copper-graphite” under working current flow and technique of its superficial improvement.
For experimental purposes the samples of М1E electric conductive copper ГОСТ 859-2001 complying with ТУ 1276-003-38279335-2013 were fabricated in dimensions of hole disks 16×6×2,5 mm in order to provide the least friction contact area for experiment acceleration. As the friction couterbody the conventional alternator brush made of graphite ГЭ-1, ГОСТ 7478-75 was used. Copper samples were strengthen by electro-spark alloying on unit ALIER-52 on 6-7 modes by aluminum electrode made of rod aluminum ГОСТ 15176-89.
The coated and uncoated samples were tested on the friction test bench М-22ПВ under “pin-on-shaft” layout. Friction speed was about 1,5-2 m/s that complies the test bench shaft rotation speed about 2000-2400 rpm. In order to simulate the brush unit work the 24 V DC voltage was applied to friction contact and linear wear rate was detected.
So uncoated samples have demonstrated the wear rate of 345,5 micrometers per kilometer, unlike coated samples hat have the wear rate 81,8 micrometers per kilometer what is about 4,26 times improvement of electro erosive wear resistance.
Thus the technique researched is suitable and can be recommended for improvement of brush units of vehicle alternators and starters, DC engines collectors for electric power vehicles, hybrid vehicles and quadracopters as well.
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Andrii Dovhal |
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H3-OB1037 |
Strength and crack resistance structural criteria of composite coatings produced by the method of multi-chamber detonation spraying Volodymyr Korzhyk1, Olena Berdnikova1, Petro Stukhliak2, Olga Kushnarova3, Junjun Zнao1, Ihor Skachkov1 1Scientific Research Institute of Welding Technologies named after E. O. Paton in Zhejiang Province, People’s Republic of China An essential task of modern industry is to increase the reliability and durability of products. One of the prospective ways to increase the products operational durability is the ceramics and cermets powders functional coatings application to the working surfaces by the method of high-speed multi-chamber detonation spraying [1]. The purpose of the given work is to establish the regularities of the influence of structural-phase features in the formed material of functional cermets coatings of metal parts on their strength characteristics and crack resistance, while taking into account structural criteria that will provide the required set of strength and crack resistance properties.
The method for thorough and detailed analysis of the structure features, morphology and distribution of phase particles, their stoichiometric composition, substructure parameters, dislocation density in the coating material obtained with help of multi-chamber detonation spraying has been developed in this work. The research of detonation coating material was performed using transmission electron microscopy (TEM) on a JEM-200CX instrument (by JEOL company) with an accelerating voltage of up to 200 kV.
The prospects of using the method of multi-chamber detonation spraying on various materials (steel, copper, aluminum, titanium) and alloys are shown based on the results of the research. A number of composite coatings made of aluminum and zirconium ceramics; chromium, tungsten carbides have been obtained. It has been established that changes occur in the ratio of the following parameters: microhardness, pore volume fraction, phase composition, distribution of dispersed phases, grain, subgrain, dislocation structures, etc, under different processing modes in the surface layers and a corresponding change in the modes of detonation spraying.
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Olena Berdnikova |
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H3-OG1320 |
Analyzing the methods for electrospark alloying with the use of multi-component special process media Oksana Gaponova1, Viacheslav Tarelnyk2, Nataliia Tarelnyk2, Piotr Kurp3 1Sumy State University, Ukraine The paper presents an analysis of technologies for improving the quality parameters of the surface layers of parts, which were carried out by the method of electrospark alloying (ESA) and by additional saturation of surfaces with alloying elements from special technological environments (STE). The technologies of sulfocementation and sulfoalitization were investigated. Metallographic and hardness tests after sulfocementing by ESA showed that the treated surface consists of layers: "soft", hardened and base metal. As the discharge energy increases, the thickness, microhardness, and integrity of the coating increase. The presence of sulfur in STE promotes the sulphidation process. It is shown that sulfur accumulates in the surface of the metal at a depth of up to 30 μm. This zone is characterized by reduced microhardness. A strengthened layer is formed under this layer, it has an increased carbon content and high microhardness. Three zones can be distinguished on the microstructures: a near-surface, non-continuous loose layer, 10-100 μm thick and a microhardness of 1368-2073 MPa, a "white" hardened layer with a thickness of 20-40 μm and a microhardness of 4094 -5157 MPa, diffusion zone and base metal. As the discharge energy increases, the parameters of the layer increase: thickness, microhardness of the upper and white layers, as well as their integrity. It is showed that the largest amount of sulfur is in the surface layer, which characterizes the layer of reduced microhardness. The diffusion zone of aluminum is 30-80 μm, depending on the energy parameters of the ESA process. The near-surface "soft" layer is enriched with sulfur, strengthened with aluminum. The phase composition of the coatings was investigated. It depends on the energy modes of alloying.
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Oksana Gaponova |
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H3-MG1811 |
The structure of boride diffusion coatings produced on selected grades of structural steels Marek Goral, Kamil Ochał, Barbara Koscielniak, Tadeusz Kubaszek, Kamil Gancarczyk, Andrzej Gradzik, Adrianna Przybyło, Jakub Jopek, Magdalena Mokrzycka, Marcin Drajewicz Rzeszow University of Technology, Poland Problem statement and objective:
The Diffusion boride coatings are characterized by high abrasion resistance, good resistance to corrosion, including high-temperature corrosion. Additionally, boride coatings are not wettable by liquid metals such as zinc or aluminium. In the article the microstructure and phase composition of boride coatings deposited on selected structural steels were described
Methods :
The boride coatings were produced using pack cementation method using commercial EKABOR-2 powder. Boride coatings were deposited on alloyed structural steels grades: C45, S355, 16MnCr5, 18CrNiMo7-6, 34CrAlMo5-10, 42CrMo4, 41CrAlMo7. Cylindrical samples with a diameter of 30 mm and a height of 30 mm were boronized in powder at 1000 oC for 4 hours in an argon atmosphere. The process was carried out in an industrial CVD Bernex BPX 325S device. The microstrucuture was analysed using scanning electron microscope Phenom XL equipped with EDS analyser. The XRD phase analysis was conducted using XTRa diffractometer (ARL). The thickess as well as phase composition was analysed on coatings formed on each grades of steels
Main results and Conclusions
The most of obtained boride coatings were charatherized by single phase structure (Fe2B). The formation of brittle FeB phase was detected on S355 and 16MnCr5 grades steels. The average thickness of the boride coatings exceeded 100 micrometers.
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Marek Goral |
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H3-MW1934 |
Growth kinetics of a silicon-modified aluminide coating on a TiAl alloy Mateusz Woźniak, Marek Góral, Barbara Koscielniak, Kamil Gancarczyk Rzeszow University of Technology, Poland Problem statement and objective:
TiAl is a titanium and aluminum alloy that is used as a structural material in high-temperature applications such as aircraft and turbine engines. To improve the mechanical properties of TiAl, it is often modified by adding other elements such as silicon. The pack cementation process is one method of modifying TiAl, which involves coating the surface of the alloy with a special mixture containing silicon, to enrich it with this element. As a result of this process, Si-modified TiAl is created, which exhibits improved mechanical properties and resistance to high temperatures, making it ideal for use in the aerospace and turbine industries.
Methods :
The powder used in the pack cementation process consisted of 20 wt.% Si, 20 wt.% Al, 1-2% NH4Cl activator, and the rest Al2O3, as well as 40 wt.% Si, 40 wt.% Al, 1-2% NH4Cl activator, and the rest Al2O3 calculated for 100 g of powder. The process was carried out at a temperature of 950°C for 2, 4, and 6 hours.
Main results and Conclusions
The following analyses were performed after the pack cementation process: scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) attachment for microanalysis, as well as X-ray diffraction (XRD).
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Mateusz Woźniak |
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H3-MW1940 |
The formation of Hf-modified aluminide coatings on TiAl intermetallics Mateusz Woźniak, Barbara Kościelniak, Kamil Gancarczyk, Marek Goral Rzeszow University of Technology, Poland Problem statement and objective:
TiAl is a promising material for high-temperature applications due to its high strength-to-weight ratio, good oxidation resistance, and excellent creep properties. However, its practical application is limited by poor ductility at room temperature and low fracture toughness. To address these issues, TiAl is often modified with other elements, such as Hf. The pack cementation process is a commonly used method for modifying TiAl with Hf, which involves coating the surface of the alloy with a special mixture containing Hf. The resulting TiAl-Hf alloys exhibit improved mechanical properties and high-temperature stability, making them attractive for use in the aerospace and automotive industries.
Methods :
The powder used in the pack cementation process consisted of 20 wt.% Hf, 20 wt.% Al, 1-2% NH4Cl activator, and the rest Al2O3 as well as 40 wt.% Si, 40 wt.% Al, 1-2% NH4Cl activator, and the rest Al2O3 calculated for 100 g of powder. The process was carried out at a temperature of 950°C for 2, 4, and 6 hours.
Main results and Conclusions
The following analyses were performed after the pack cementation process: scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) attachment for microanalysis, as well as X-ray diffraction (XRD).
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Mateusz Woźniak |
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H3-MS1229 |
Microstructure and wear behavior of plasma sprayed (Ti,Cr)C-Ni composite coatings Maryna Storozhenko1,2, Oleksandr Umanskyi1, Oleksiy Melnyk3, Oleksandr Terentiev1, Tetiana Chevychelova1, Viktor Varchenko1, Oleksandr Koval1, Valeriy Brazhevsky4, Oleksandr Chernyshov4 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Thermally sprayed cermet coatings are widely used in many engineering applications to protect against wear and corrosion. (Ti,Cr)C can be applied as starting component to produce wear-resistant coatings. As a solid solution, the (Ti,Cr)C is expected to possess the main advantages of TiC with higher oxidation resistance owing to the formation of Cr2O3. In order to improve the fracture toughness and cohesion of coatings, the metal or alloy powder are introduced as the binder into (Ti,Cr)C-based composite powders.
In the present work, the (Ti,Cr)C-based composite powders with different Ni binder content (18, 25, 33 wt.%) were deposited onto steel substrate by plasma spraying. The aim was to investigate the influence of Ni content on the microstructure, coefficients of friction, and wear rates of plasma sprayed (Ti,Cr)C-Ni coatings, and the wear mechanisms was also discussed. The microstructure and dry sliding wear resistance of the (Ti,Cr)C-Ni coatings were investigated. The (Ti,Cr)C-Ni coatings have a heterogeneous structure composed of (Ti,Cr)C particles and Ni binder. Fracture and partial dissolution of the (Ti,Cr)C particles were found to occur during the plasma spray process. Among all the tested coatings, (Ti,Cr)C-33wt.%Ni coating exhibits lower wear rates and friction coefficients under all conditions. Worn surfaces of the coatings were analyzed using SEM to investigate the wear mechanism. The main wear mechanism of the (Ti,Cr)C-18wt.%Ni is a combination of abrasive wear and delamination phenomena, while the (Ti,Cr)C-25wt.%Ni shows adhesive wear. The (Ti,Cr)C-33wt.%Ni coating exhibits high wear resistance due to the realization of the tribo-oxidation wear mechanism.
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Oleksiy Melnyk |
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H3-AC1300 |
Modeling of gas-discharge processes and formation of diffusion discrete-matrix structure of tube inner surface by ion - plasma nitriding Ihor Smyrnov, Anatolii Kuzmichev, Leonid Tsybulsky, Andrii Chornyi, Volodymyr Lysak National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” The ion-plasma nitriding is used for obtaining diffusion surface layers with high corrosion, wear and crack resistance. This technology is also attractive for forming a promising discrete-matrix structure of the inner surface of steel tubes, but there is a problem of processing in closed space inside the tubes of small diameter and large length. This work is devoted to this problem.
The nitriding of inner tube surface was realized in a coaxial discharge system with the tube as a cathode and the internal electrode as an anode. The anode also was a tube and had side holes through which the working gas (Ar+N2) was admitted into the tube. A pulsed DC power supply provided support for an anomalous glow discharge for heating and ion treatment of the tube inner surface. The COMSOL software was used to simulate the gas processes in the tube cavity.
Modeling of the gas flow has showed its multi-jet nature, in which individual streams were formed by gas flowing out of individual anode holes. The configuration of these streams was influenced by the magnitude of the total working gas flow and the diameter of the anode holes. In places where individual gas streams hit the tube inner surface, a local increase in gas density and nitrogen concentration and, respectively, a variation in the conditions for ion bombardment along the cathode surface were observed. Then it was experimentally found that ion-plasma nitriding of tube inner surfaces with gas providing through the perforated internal anode led to the formation of diffusion coating consisting of areas with different chemical and phase composition, that is the same areas contained the solid phase from iron nitride in a soft matrix of alpha iron, which corresponds to a discrete-matrix coating. Based on the obtained results, it can be assumed that the multi-jet outflow of the working gas through the anode holes makes it possible to format of a discrete-matrix diffusion coating on the inner surface of the steel tube.
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Ihor Smyrnov |
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H3-AK2232 |
Thermophysical properties of lanthanide di-titanates Alla Kopan', Mykola Gorbachuk, Sergij Lakiza, Alina Makudera, Dmytro Korablov Frantsevich Institute for Problems of Materials Science of NASU, Ukraine The rare earth di-titanates are of great interest for materials scientists due to their many technological applications. The Ln2Ti2O7 oxides in the perovskite-like structure have high-temperature piezoelectric and ferroelectric properties. Materials with the pyrochlore structure are attractive as ceramic thermal barrier coatings (TBC), potential solid electrolytes in solid oxide fuel cells and immobilization hosts of actinides in nuclear waste. Some members of the series are also very important for the aeronautical engineering, aerospace and power generation industries. At the same time, many of its properties, especially its thermophysical properties, have not yet been investigated.
The objective of this research is to study the thermophysical properties of Ln2Ti2O7 (Ln = Pr, Nd, Eu, Yb) complex oxides. The rare earth di-titanates samples were characterized by X-ray diffraction. The measurements of thermal conductivity of Ln2Ti2O7 sintered pellets were carried out for the first time in interval 313-673 K in the monotonous heating mode using the dynamic calorimeter method.
The thermal conductivity of the rare earth di-titanates does not show the classical dependence and reaches an almost temperature-independent value above ~ 673 K. Among investigated samples, the pyrochlore-type Eu2Ti2O7 and Yb2Ti2O7 oxides demonstrate the lowest thermal conductivity and the highest k-values, respectively. These results are similar to those found in literature for their hafnate analogues. It has been shown that the Ln2Ti2O7 thermal conductivity values are lower than those for Ln2Hf2O7 in the all temperature range of measurements.
The specific heat temperature dependences of the rare earth di-titanates were calculated according to the Neumann-Kopp law for the first time and then that were used for computation of thermal conductivity.
In conclusion, the Ln2Ti2O7 phases might be attractive component materials for creating new thermal barrier coatings.
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Alla Kopan' |
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H3- I1547 |
The surface layers formation in Fe-alloys by electric-spark alloying and carbonitriding Galina Lobachova, Ievgen Ivashchenko National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” Electric-spark alloying (ESA) leads to increase of the metal surface hardness and chemical heat treatment can increase the length of the hardened areas into deep of the details. It is possible to create surface areas that have high microhardness, which prevents deformation and fracture at high loads on the surface in the case of consistently carrying out these processing techniques.
Objective: to study the structure, phase composition and microhardness of the Fe-alloys (Fe + 1,5 wt.% Ti; Fe + 2,5 wt.% Cr; Fe) surface at ESA by Ti and Cr and subsequent Carbonitriding.
ESA of samples by Cr- or Ti-anodes was carried out at working voltage 70 V, current 2 A during 3 minutes in air.
Carbonitriding was carried out at temperature 580ОC during 30 minutes.
The structure, microhardness and phase composition of diffusive areas were studied with the use of microstructural, microhardness and X-ray diffraction analysis.
It is shown that after carbonitriding microhardness of Cr- and Ti-coating increases to 7,4-9,9 GPa and 9,9-13,9 GPa depending on the base materials. Titanium coatings have higher microhardness than chromium, due to the strong interaction of Ti with penetration elements (C, N) to form a dispersion of carbides, nitrides, carbonitrides.
As a result of X-ray analysis of iron after ESA by Ti + carbonitriding the (-Fe, Ti, Fe2Ti and nitrides Fe2N, Fe3N were defined; after ESA by Cr we defined the a solid solution of α-(Fe,Cr), carbides Cr3C2, Fe3C and nitrides Fe2N, CrN.
Established that previously applied coating act as a barrier to the penetration of nitrogen and carbon in the succeeding carbonitriding, which reduces the length of hardened layers alloys (Fe + 1,5 wt.% Ti; Fe + 2,5 wt.% Cr). Titanium coating reduces the diffusion length of the zone from 370 to 230 microns in alloys Fe + 1,5 wt.% Ti and from 230 to 180 microns in alloys Fe + 2,5 wt.% Cr in comparison with chrome from 370 to 340 microns and from 230 to 220 microns, respectively.
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Ievgen Ivashchenko |
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H3-VP2125 |
Tribology Properties of Ti₂AlC MAX Phase Based Coatings Deposited By Vacuum Arc Method Viktoriya Podhurska1, Olexander Kuprin2, Roman Chepil1, Orest Ostash1, Tetiana Prikhna3, Volodymyr Sverdun3, Margaryta Bortnitskaya2, Igor Kolodiy2, Vitalii Belous2 1Karpenko Physico-Mechanical Institute of NASU, Ukraine Improving the durability of aircraft engine tribo-couplings that operate in high-temperature and dry friction is an urgent task. The Ti-Al-C MAX phases and their corresponding coatings have a low specific wear rate, mainly due to the formation of specific oxide layers in the friction zone.
The purpose of this work is to investigate the tribological properties of Ti-Al-C coatings at two temperatures, 25°C and 500°C.
The Ti-Al-C coatings were deposited on polished stainless steel samples using a Ti₂AlC MAX phase cathode and the vacuum arc method. TiN coatings were used for comparison. The composition and structure of the coatings were analyzed using XRD, SEM, and EDX methods. Mechanical properties were investigated using a Nano Indenter G200 nanohardness tester. Friction coefficients and wear resistance were tested by reciprocating motion between plates with coatings and a steel ball.
Composite coating consisting of two phases TiC and Ti₃AlC is formed at a potential of -50 V, and at a potential of -100 V, an aluminum-depleted composite is formed TiC+α-Ti. Tribological tests showed that for TiC+Ti₃AlC coatings, the coefficient of friction is µ =0.7 -0.8, and the wear rate w increases from $7.56\cdot 10^{-4}$ at 20°C to $1.81\cdot 10^{-3}$ mm³/Nm at 500°C. TiC+α-Ti coatings have a coefficient of friction at the level of µ =0.5-0.6, and w decreases from $1.26·10^{-4}$ at room temperature to $7.18\cdot 10^{-5}$ mm³/Nm at 500°C in contact with a ball made of steel ШX15. The wear resistance of these coatings is 1.5…2 times higher compared to TiN coatings. There is no definitive correlation between the mechanical properties and the tribological characteristics of the materials.
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Olexander Kuprin |
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H3-JŠ1306 |
Surface laser boronizing of maraging steel parts manufactured by selective laser melting Kęstutis Bučelis, Jelena Škamat, Olegas Černašėjus Vilnius Gediminas Technical University, Lithuania Maraging steel (MSt) is known as a special class of high-strength steels with the specific alloying system providing highly alloyed low-carbon iron-nickel lath martensite matrix, which is aged (annealed) to obtain hardening by intermetallic precipitation. Recently, this steel has been increasingly used in the field of additive manufacturing because it has high resistance to thermal cracking and can be used in the production of parts by selective laser melting. Despite the yield strength of MSt reaches high values (up to ~2420 MPa for commercial grades), it has moderate hardness (~58 HRC max.) and, as a result, insufficient wear resistance under severe working conditions. In the present study, the surface laser alloying process is investigated as a possible way to improve wear resistance of MSt parts.
The samples manufactured by the SLM method and heat treated at 840 (2 h) and 490 (2 h) degrees were coated with a layer of amorphous boron 0.03-0.6 mm thick and processed with a laser beam at different laser speeds (500-1500 mm/min), providing a treatment in a melting mode. The alloying process was performed with the preheating the samples to 400 degrees. Boronized layers in a wide range of hardness from 490 to 2200 HK0.2 with a structure from hypo-eutectic to a mixture of borides were obtained. The effect of the thickness of pre-placed boron paste layer and laser speed on the molten pool geometry and formation of boronized layer was investigated. The nature of cracks formed was studied as well. The hardness distribution along the layers depth and the influence of processing parameters on the softening effect and thickness of the heat affected zone were studied. Two-body dry sliding wear test was conducted to assess their wear resistance. All boronized samples showed an improvement in wear resistance (on average up to ~7.5 times), with the exception of samples having the lowest hardness ~ 490 HK0.2.
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Kęstutis Bučelis |
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H3-SK1639 |
Morphology and properties of nickel deposits obtained by electrocrystallization in a weak induction magnetic field Stanislav Kovalyov, Oleg Girin, Volodymyr Ovcharenko, Vladyslava Mishchenko Ukrainian State University of Chemical Technology, Ukraine Nickel deposits of machine parts are used in industry as functional coatings. This is due to the fact that they have high hardness, excellent reflectivity and high resistance to corrosion damage. It is known that a weak induction magnetic field affects the electrocrystallization and properties of copper deposits. The aim of our work was to establish the relationship between the morphology of nickel deposits obtained in a weak induction magnetic field. And evaluate the influence of deposition conditions on the physical and mechanical properties of deposits.
Methodology. Electrocrystallization of nickel deposits was carried out from a solution containing, mol/l: NiSO47H2O - 0.64, NH4Cl - 0.5, H3BO3 -0.49. The current density is 3 A/dm². A uniform magnetic field with an induction of 1 mT was created around the electrochemical cell. The surface morphology was studied using scanning electron microscopy. The reflectivity was measured with an FB-2 photogloss meter. The microhardness of the deposits was measured with a PMT-3 microhardness tester.
Results. In our work, we have shown that electrocrystallization of nickel in a weak-induction magnetic field affects the electrodeposition process, morphology, and properties of the deposit obtained. The presence of a magnetic field leads to a decrease in the size of grained aggregates. Deposit was obtained close-packed, which affected the reflectivity. The reflectivity was 74% compared to the silver mirror. The microhardness of nickel deposits obtained by electrocrystallization in a magnetic field was, in comparison with the deposits obtained without a magnetic field, increased by more than 1.3 times. The data presented in the work show that the magnetic field affects the properties of deposit.
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Vladyslava Mishchenko |
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H3-MG2053 |
The influence of plasma spraying parameters on microstructure and porosity of bronze-polyester coatings for plain bearings applications Marek Góral, Tadeusz Kubaszek, Barbara Koscielniak Rzeszow University of Technology, Poland The plasma sprayed bronze coatings are widely used for repairing of plain bearing used in different applications. This type of coating was not deeply analyzed in state-of-art publications. In presented article we fill this gap in the case of plasma spraying process.
The influence of power current (I=300/500/700A) and hydrogen flow (0/4/8 NLPM) on microstructure and thickness of aluminium bronze-polyester coating was investigated. The Thermico A60 plasma torch was
used for thermal spray process of coating on flat carbon steel samples (grade S355). The Metco 604NS powder was plasma-sprayed with 20 g/min powder feed rate. The obtained results showed the presence of
local large pores formed by burning of polyester in plasma plume. This pores observed in microstructure plays role of oil pockets in bearings. The obtained coatings were characterized by large deviation in
thickness in range 200-350 micrometers and high porosity about 20 vol. %.
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Marek Góral |
Low-dimensional and NanoMaterials_program_list
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H3-OO1107 |
Reduced graphene oxide in metal oxide thermoelectrics Olena Okhay1, Oleksandr Tkach2 1TEMA- Center for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, Portugal Today the energy demands are exponentially rising, and the worldwide research is focused on the clean and sustainable energy sources during the last years. As one of the possible ways to enable the transformation from a fossil fuel based to a low-carbon socio-economical epoch is the harvesting of unused heat in automotive exhaustion, industrial processes and home heating, etc.
Thermoelectric (TE) generators can convert the heat to electrical energy thanks to Seebeck effect when electricity appears between cold and hot ends of usually semiconductor materials. To be interesting for potential commercial use in TE generators the materials need to be of high figure of merit (ZT), possessing high electrical conductivity and Seebeck coefficient together with low thermal conductivity. Driven by a need to improve TE performance of n-type oxides, ceramics and composites based on donor-doped SrTiO3 are considered as a promising material.
Addition of reduced graphene oxide (rGO) in combination with introduction of Sr vacancies provides a synergistic effect of fastening charge transport in Nb-doped SrTiO3 and thereby increasing electrical conductivity and suppressing thermal conductivity.
The increasing electrical conductivity and suppressing the thermal conductivity, together with a moderate Seebeck coefficient, result in a high power factor PF ∼1.98 mW/(K2m) and ZT up to 0.29. Such findings offer further prospects for seeking high performance SrTiO3-based TEs by modification with rGO. Deep comparison with other thermoelectric composites with rGO is done.
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Olena Okhay |
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H3-MD1847 |
The structure and characteristics of all-dielectric opal-based nanocrystalline composites Mykhailo Derhachov1, Vasyl Moiseienko1, Bilal Abu Sal2 1Oles Honchar Dnipro National University, Ukraine Fabrication of opal-based composites with regularly spaced nanocrystals of active dielectrics is of a significant interest. Having a permittivity period close to light wavelength, these structures could be applied in light manipulating systems. Crystallization under specific conditions could result in changing initial substance parameters and forming the other phases. Herein, we examinate properties of nanocomposites fabricated by melt infiltration process with exploiting dielectrics, prospective for applying in optoelectronics (NaBi(MoO4)2, Pb3(P0.5V0.5O4)2, Bi12(Si)GeO20, Bi2TeO5, Li2B4O7).
Initial opals were porous matrices formed by the 250 nm SiO2 particles. The composite fabrication technique was based on capillary forced infiltration of initial opals with wetting melt of the input component. Characterisation was made with SEM, XRD, impedance and Raman spectroscopy techniques.
XRD patterns and Raman spectra indicate the nano-crystalline state of the embedded substance. Formation of nanocrystals is caused by mesoporous structure of SiO2 particles served as multi-crystallization centres. An average linear size of nanocrystals, derived from the XRD paterrn, does not exceed 30 nm for all composites, and it is well correlated with that defined from the impedance data in opal-NaBi(MoO4)2 composite. The change of lattice parameters is detected. With embedding Bi12Si(Ge)O20 and Bi2TeO5, the Bi4Si3O12 and α-cristobalite phases are additionally formed. The α-quartz phase is formed in opals soaked with the Li2B4O7 melt. Meanwhile, no stoichiometry deviations and new phases are detected in opal-NaBi(MoO4)2 and opal-Pb3(P0.5V0.5O4)2 composites. The observed changes are explained by interaction of the broken Si–O bonds on the SiO2 particle surface with Bi and Li ions, considering their charge state and concentration. Thus, the most stable components for melt infiltration process and ways to vary the composition have been found.
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Mykhailo Derhachov |
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Poster session Important.session is online-only and include 5 min presentation in the common conference room and 1 hour of discussion in individual rooms (Zoom) |
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H3-MB1006 |
Synthesis of multi-walled carbon nanotubes by the method of chemical deposition from methane air conversion products Alexander Khovavko1, Denis Filonenko1, Alexey Svyatenko1, Andriy Nebesnyi1, Anastasiya Kolesnichenko2, Yeva Boboshko2,3, Maksym Barabash1,2,3 1The Gas Institute, N.A.S of Ukraine The method of carbon nanotubes (CNTs) synthesis by chemical vapor deposition (CVD) is currently modern and widely used in industry [1,2]. Important factors affecting the synthesis of CNTs by the CVD method are: the choice of precursor gas, temperature and pressure in the reaction chamber, gas flow rate, nature and size of the catalyst grain [3]. The CNTs synthesis process was carried out using the products of air conversion of natural gas as raw material. The classical spectrum of carbon nanotubes with two characteristic peaks at 1298 and 1586 cm-1 corresponding to D and G modes, respectively. At the same time, on the first, second, and fourth spectra, classical spectra for nanotubes with characteristic D- and G-modes are clearly observed. However, it was found that in all three samples the D mode has a higher intensity than the second mode, which is not characteristic for single-walled intact nanotubes. That is, it can be concluded that the nanotubes obtained in our experiment by CVD method are multi-walled and most likely have a curved structure. In all three samples, a shoulder in the G mode is clearly visible (which may be an overtone of the D mode) and indicates the high defectiveness of the obtained samples. Raman spectra confirmed the presence of carbon nanotubes with two characteristic peaks at 1310 and 1578 cm-1 corresponding to D and G modes, respectively. Based on the ratio of the two modes, the ratio of the planes under the G and D bands was calculated and a significant number of carbon nanotubes defects was determined. According to the peak half-width parameter D, it can be clearly determined that the samples have the smallest peak half-width, which indicates their highest crystallinity. All nanotubes, according to the calculated ratios, have a high number of defects and bends, however, sample number 2 has the most perfect (smallest number of defects) compared to the others.
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Maksym Barabash |
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H3-OL1221 |
Nanostructured photocatalytically active TiO2-based nanocomposite systems Olena Lavrynenko, Maksim Zahornyi, Olesja Pavlenko, Serhiy Korichev I. Frantsevych Institute for Problems of Materials Science of NAS of Ukraine Titanium dioxide is widely used for remediation of organic dyes in wastewater, but its application requires exposure to UV radiation due to the wide band gap (Eg~3.2 eV). Various elements are injected into the structure to extend the activity of TiO2-based catalysts to the visible light region. The aim of the work is the synthesis of TiO2-based nanocomposite systems and the verification of their photocatalytic activity for the discoloration of the malachite green (MG) water solution. The synthesis of the nanocomposites was performed via the co-precipitation of TTIP with the Ag, Au, and Ce-containing species (0.2-4.0 wt.%). The precipitates were washed, filtered, lyophilized at 120 °C and calcined at 600 °C in 2 h. Composite particles were studied by XRD-analysis, SEM, and an energy-dispersive spectroscopy. The photocatalytic activity of the systems was tested using a MG water solution (20 mg/dm3) at pH 7. Dispersion was stirred in the dark and then stirred under UV (254 nm). XRD data showed the formation of anatase for all studied systems. Lattice parameters are the following: a – 0.3740÷0.3778 nm, c – 0.9428÷0.9645 nm, V – 0.133÷0.136 nm3. CSR of pure TiO2 is 12.7 nm, and CSR of the nanocomposites is 8.3-10.6 nm. Right shift of the (101) plane is typical for the all samples. The tetragonality degree of TiO2&Au and TiO2&Ag samples is 2.51, but it increases to 2.57 for TiO2&CeO2 composites. Decolorization of the MG solution under UV irradiation in 5 min increases in the row TiO2&Au < Pure TiO2 < TiO2&CeO2 < TiO2&Ag < TiO2&CeO2&Ag. However, the clusters of Ag on the anatase surface are oxidized under UV in contact with the MG in 45 min. Also, TiO2-based nanostructures exhibited sorption activity in the dark. The degree of MG decolorization was more than 95% even after 5 min of contact. Thus, the obtained nanostructures are promising materials for creating photoactive catalysts for MG destruction.
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Olena Lavrynenko |
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H3-AD2223 |
Modeling of photovoltaic characteristics of a TiO2/porous-Si/Si-based heterojunction solar cell Alena Dyadenchuk Dmytro Motornyi Tavria State Agrotechnological University, Ukraine Recently, the issues of increasing the conversion coefficient of solar energy into electrical energy, identifying ways to increase efficiency, and reducing the electricity cost have been predominant in microelectronics. Тhere is a need to replace monocrystalline silicon with other promising materials. The purpose of the paper is to conduct simulation and optimization of the functional characteristics of the photoconverter based on heterostructures TiO2/PS/Si.
Simulation is proposed to conduct in a freely distributed program PC1D. During the simulation, the thickness of the layers was varied from 100 nm to 1.0 μm for the PS and TiO2 layers, respectively, the concentration of the main charge Nd carriers from 10^13 to 10^20 cm-3. The values of the main physical parameters used in the modeling of solar cells are obtained from scientific sources.
Simulation has shown that changing the thickness of the porous layer does not significantly affect the short circuit current at the selected values (Isc=33.5 mA). At a thickness of 0.2 μm, the efficiency of the solar cell is on a maximum value, but with an increase in the thickness of the porous layer, a decrease in efficiency from 21.3 % to 21.0 % is observed. In this case, there is also a decrease in Voc values from 0.799 to 0.798 V. The analysis of the data shows that increasing the doping level of the PS layer from 10^13 to 10^19 cm-3 leads to an increase in the short circuit current Isc. The efficiency increases from 18.0 % to 22.3 %. It can be seen that the dependence of the open circuit voltage Voc on the level of the layer doping is weak and decreases by 16.8 mV. The optimal thickness of the TiO2 layer is d=100 nm. The analysis shows that increasing the TiO2 layer doping level from 10^13 to 10^20 cm-3 has no particular effect on the short circuit current value, but at Nd=1∙10^20 cm-3 this value decreases by 0.4 mA. Changing the doping level Nd has little effect on the no-load voltage.
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Alena Dyadenchuk |
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H3-YY0561 |
Impact of mechanical treatment duration on the structure of nanopowder composite SiO2/TiO2 Yurii Yavorskyi1,2, Myroslav Karpets1,2, Andrii Hrubiak3, Oleksandr Dudka1,2, Tiancheng An1,2, Yulong Guo1,2 1Y.O.Paton ER IMW, Ukraine The properties of nanosized materials depend on their structural and morphological features, electronic structure, development and surface defects, and others. Different methods of synthesis and processing are used to increase the surface activity of materials. One of the methods that allows to achieve this is machining, and in this case mechanical treatment on the microbreaker (MBT) [1,2]. In this work, we conducted a study of the effect of different duration of such treatment on the structural and morphological features of the mixture 0.8SiO2+0.2TiO2. Preparation of the initial mixture was performed by conventional stirring for 5 minutes, followed by stirring in a 50 Hz mechanical microbreaker Ardenne with stainless steel sphere (25 mm in diameter) and ball (10 mm in diameter). Mechanical processing was carried out under the same conditions, but for 3, 5, 10, 15 and 20 minutes. The morphology of the nanoparticles before and after MBT was studied using scanning electron microscopy (SEM) PEM-106. The crystalline structure of the powder blends were studied using the Ultima IV diffractometer (XRD). From the results of SEM studies, it was established that a uniform distribution of oxide agglomerates occurs in the mixture after 3 min of MBT; 5 minutes of processing leads to fragmentation of these agglomerates and the formation of new ones from nanoparticles of both oxides; Processing for 10-20 minutes leads to an increase in the density of the nanocomposite. From the results of XRD, it was found that anocomposite consist of amorphous SiO2 and two phases of TiO2 (rutile, anatase). As a result of MBT for 3 and 5 min, the coherent region scattering (CRS) of rutile decreases and anatase increase. Subsequent MBT for 10-20 min is accompanied by its rapid increase of CRS of rutile and normalize anatase. It should be noted that the changes in lattice parameters and phase composition were within the error limits of the experiment.
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Yurii Yavorskyi |
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H3-NK2053 |
Electrochemical properties of 2D MoS₂/Mo nanocomposites Leonid Kulikov, Nataliia Konih-Ettel, Victor Talash, Yuliia Rudenko, Mykolai Shevchuk Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Recently, the development of 2D transition metal chalcogenides (TMDs) nanomaterials with a variety of physicochemical properties has shown their potential as eminent non-noble metal-based nanoscale (photo)electrocatalysts for hydrogen evolution (HER).
Electrochemical properties of 2D MoS₂/Mo nanocomposites were studied in 0.5M H₂SO₄ electrolyte by using potentiodynamic polarization curves method. It was used Platinum as the counter electrode and Ag/AgCl as the references.
Sufficient chemical stability of the MoS₂ nanocoating on Mo was established, as well as the possibility of the formation of intercalated H⁺ₓ(H₂O)ᵧMoS₂₋ₓ/Mo nanophases at the removing process of cathodic polarization curves.
The pre-treatment annealing of the MoS₂/Mo nanocomposite in the air (400 K, 1 h) was performed to study the surfaces oxidation effect on the cathode polarization curves (as to the synthesis of MoO₃₋ₓ/MoO₃ layer on their surface and the formation of complex MoO₃₋ₓ/MoO₃/MoS₂/Mo nanocomposite).
The iodine pre-treatment (halogenation) of MoS₂/Mo nanocomposites was carried out as to the possible formation of intercalated IₓMoS₂/Mo compounds, and their effect on polarization curves and increasing of the electrical conductivity.
The obtained results clearly indicate to the positive role of the pre-treatment annealing and halogenation of the initial MoS₂/Mo nanocomposites, what leads to a significant increase in the electrical conductivity (an increasing of current density by almost order of magnitude at -1.5 V).
2D MoS₂/Mo nanocomposite has the potential as electrocatalysts for HER, suggesting the development of new type of catalyst with efficient activity in HER as well as other renewable energy fields.
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Nataliia Konih-Ettel |
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H3-TV1732 |
Phase formation in layered Pd/Ag/Fe films and their magnetic properties during annealing in hydrogen Oleksandr Sliesarenko1, Leonid Levchuk1, Maryna Natalenko1, Katerina Graivoronska2, Ruslan Shkarban1, Tetyana Verbytska1, Iurii Makogon1, Sergiy Sidorenko1 1Y.О. Paton Educational and Research Institute of Materials Science and Welding National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” Nanoscale films based on FePd with an ordered structure are promising for use as ultrahigh-density magnetic recording media, future spintronic memory and logic devices.
The aim was the investigation of thermal treatment environment, intermediate Ag layer thickness and annealing temperature influence on the phase composition, structure and magnetic properties of the films. Layered Pd(6 nm)/Ag(0.2; 0.4 nm)/Fe(4.6 nm) and Pd(7 nm)/Ag(0.2; 0.4 nm)/Fe(5 nm) films to form Fe 49 Pd 51 and Fe 47 Pd 53 compositions after annealing were deposited on a SiO 2 (100 nm)/Si(001) substrate by magnetron sputtering. Thermal treatment was carried out in three modes: annealing in H 2 in the range of 600 °C - 700 °C for 1 hour, Rapid thermal annealing (RTA) in nitrogen for 90 s, and two-stage heat treatment (RTA + annealing in H 2 ) at 600 °C and 650 °C. The films were investigated by X-ray analysis, SQUID and AFM methods.
Іn the as-deposited Pd(6 nm)/Ag(0.2 nm)/Fe(4.6 nm) film a low intensity Pd(111) reflection is observed. Annealing in H 2 at 600 °C is accompanied by mutual diffusion between the layers with the formation of Pd(Ag, Fe) solid solution. An increase in the Ag thickness to 0.4 nm activates these processes leading to the formation of a soft magnetic disordered A1 FePd phase. An increase in the annealing temperature to 650 °C leads to rise in the coercivity. This is explained by a larger amount of Ag along the FePd grain boundaries, which limits their growth and reduces the exchange interaction. Two-stage heat treatment and an increase in the annealing temperature to 650 °C in both films also lead to the A1 phase formation. It was established that in the Pd/Ag/Fe films, regardless of the thickness of the Ag interlayer, annealing in H 2 in the range of 650 – 700 °C is accompanied by the formation of a disordered A1 phase. Variation in the film composition from Fe 49 Pd 51 to Fe 47 Pd 53 leads to changes in the saturation magnetization which is associated with an electronic structure change.
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Tetyana Verbytska |
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H3-RP2357 |
Diffusion-induced local ordering in Pt/Co bilayers Roman Pedan1, Pavlo Makushko1,2, Oleksandr Dubikovskyi1,3, Andrii Bodnaruk1,4, Andrii Burmak1, Denys Makarov2, Igor Vladymyrskyi5 1National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” Magnetic materials based on Co-Pt alloys have great potential as materials for spintronics and data storage applications [1]. Therefore, it is important to study the diffusion and formation of ordered magnetic phases in thin films made of Co and Pt. In current study Pt(14 nm)/Co(13 nm)/Ta(3 nm) stacks were magnetron sputtered on substrate and then annealed in a high vacuum at temperatures ranging from 200 °C to 550 °C with a constant annealing duration of 30 minutes. Several techniques including secondary ion mass spectrometry (SIMS), X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and VSM magnetometry, have been used to analyze the structure, chemical composition, and magnetic properties of the post-annealed stacks. Although the formation of ordered L10-CoPt phase and the achievement of long-range chemical order was not observed, heat treatment increased the coercive field and created local anisotropy in the CoPt film. These results suggest the need for further investigation into diffusion processes and the formation of hard magnetic phases through a diffusion-induced grain boundary migration mechanism in Co-Pt thin films during low-temperature annealing.
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Roman Pedan |
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H3-SG1252 |
Local straine strengthening of the low-carbon steels near inclusions by severe plastic deformation Svetlana Gubenko1,2 1Iron and Steel Institute of Z. I. Nekrasov National Academy of Science of Ukraine The aim of this work was to study the local processes of plastic structure formation occurring in low-carbon steels near non-metallic inclusions during severe plastic deformation by the method of equal-channel angular pressing.
Samples of steels were subjected to plastic deformation by the ECAP method in four passes which corresponded to a true deformation of 3.2. Structural analysis was performed using an Olympus PME 3 optical microscope, as well as JEM 100CX and JXA-50F electron microscopes.
In the steels under study, structure formation during severe plastic deformation is associated with the formation of oriented structural elements that have dimensions of 100…260 nm and are separated by high-angle boundaries, which are characterized by the presence of dispersed curved mesobands of deformation, and in steel 08Kh18N10T also martensitic plates. Near the inclusions, the grain sizes are significantly smaller than far from them and are 75…100 nm. The nanohardness values of the steel matrix near the inclusions were 25…40% higher than the similar values far from the inclusions. Near plastic inclusions of sulfides and silicates, the values of nanohardness are lower than near non-deformable oxides and titanium carbonitrides, which is associated with a certain deformation relaxation of stresses in the plastic inclusion-matrix system. In cases of localization of dynamic cold recrystallization near inclusions, the nanohardness of the steel matrix decreased by about 10%.
The influence of non-metallic inclusions on the local refinement of the steel microstructure is an important effect during severe plastic deformation, which makes it possible to obtain additional nanostructural strengthening near the inclusions during the general refinement of grains to a submicrocrystalline state.
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Svetlana Gubenko |
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H3-AK1057 |
Quality factor of metal nanoparticles having the shape of a bicone and a bipyramid Andrii Korotun1,2 1National University Zaporizhzhia Politechnic, Ukraine Currently, there is an intensive search for the forms of metal nanoparticles in order to achieve certain optimal optical characteristics. So, for example, it is assumed that nanoparticles
with sharp edges and vertices are capable of producing a local amplification of fields near the edges and, especially, at the vertices, that is greater than nanoparticles of other shapes.
Therefore, the study of the optical properties of such particles is an urgent task.
The paper investigates the size-frequency dependence of the diagonal components of the quality factor tensor for particles in the form of
bicones and bipyramids located in a dielectric medium with a permittivity $\epsilon_{\text{m}}$. This dependence is determined by the relation $Q^{\bot ( \parallel)} \left(\omega \right)=\frac{\omega}{2\operatorname{Im}\epsilon^{\bot(\parallel)(\omega)}} \left(\frac{d}{d\omega}\operatorname{Re}\epsilon^{\bot(\parallel)}( \omega )\right)$,where $\omega$ is the frequency of the incident light; $\epsilon^{\bot(\parallel)}(\omega)$ are the diagonal components of the dielectric tensor of the nanoparticle material, determined in the Drude model. To determine the size-frequency dependence of the quality factor of bicones and bipyramids, the “equivalent” spheroid approach proposed in [1] is used. Moreover, for bicones and bipyramids with $h>2r$ and $h>2r_{\text{red}}$ (where $r_{red}$ is the “reduced” radius of the base of the bipyramid, determined from the condition of equality of the areas of the bases of the bicone and bipyramid), the equivalent is a prolate spheroid, and in the case of $h<2r$ and $h<2r_{\text{red}}$, an oblate spheroid.
Calculations of the frequency and size dependences (at the frequency of the surface plasmon resonance) of the dependences of the diagonal components of the Q-factor tensor were carried out for nanosized
bicones and bipyramids made of different metals and having different sizes. It has been established that for prolate bicones and bipyramids to $Q^{\bot }\gg Q^{\parallel }$, while in the case of oblate bicones
and bipyramids, vice versa $Q^{\bot }\ll Q^{\parallel }$. In addition, in the visible region of the spectrum, the maximum $Q^{\bot }$ for $Q^{\parallel}$ Au and Ag bicones and bipyramids. The range of aspect
ratios at which the quality factor of plasmonic nanostructures of the studied forms will be maximum has been determined.
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Andrii Korotun |
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H3-AK1125 |
Features of the spectral characteristics of a metallic nanotube of variable thickness Roman Malysh1, Andrii Korotun1,2, Igor Titov3 1National University Zaporizhzhia Politechnic, Ukraine It is known that metallic cylindrical shells have unique optical properties, in particular, good spectral tunability in biological transparency windows. At the same time, the vast majority of research is devoted to cylindrical shells of constant thickness [1], and the optical properties of shells of variable thickness (non-axial cylinders) have not been practically studied, and therefore this problem is relevant. Since the wavelength of the incident light is much larger than the characteristic transverse dimensions of the considered nanostructure, to solve this problem, one can use the quasi-static approximation, in which the study of the boundary value problem of electrostatics makes it possible to obtain the frequency dependence of the polarizability. In turn, the zeros of the numerator and denominator of the expression for polarizability give dimensional dependences for the frequencies of invisibility and surface plasmon resonance (SPR).
Calculations of the size dependences and dependences on the permeability of the inner cylinder of the SPR and invisibility frequencies were carried out for non-coaxial cylindrical two-layer nanostructures in which the inner cylinder is made of dielectrics and the shell is made of noble metals. The presence of four invisibility and SPR frequencies has been established, and for structures $\text{Si}{{\text{O}}_{2}}\text{Au}$ and $\text{Si}{{\text{O}}_{2}}\text{Ag}$ the splitting of the lower and upper frequencies of invisibility and the lower branch of the SPR frequency is very small.
In addition, for these nanostructures, the invisibility frequencies are practically independent of the distance between the axes of the cylinders, the lower SPR frequencies decrease, and the splitting of
the upper frequencies increases with increasing distance. It is shown that all four frequencies of invisibility and SPR decrease with an increase in the dielectric constant of the inner cylinder, and the
decrease in the lower frequencies is more significant than the upper ones.
It is shown that when the distance between the axes of the cylinders tends to zero, two upper and two lower frequencies of invisibility and SPR merge, as in the case of a metal shell of constant thickness.
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Roman Malysh |
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H3-MM1135 |
Plasmons in a chain of prolate metallic nanospheroids Maksym Maniuk1, Andrii Korotun1,2, Valery Kurbatsky1, Igor Titov3 1National University Zaporizhzhia Politechnic, Ukraine Periodic chains of metal nanoparticles of various shapes attract the attention of researchers, since they are systems in which the plasmon propagation length turns out to be a macroscopic quantity. This makes it possible to use chains of nanoparticles as plasmonic waveguides in telecommunication technologies, which makes the study of the plasmonic properties of such nanosystems an urgent task.
When the distance between the particles in chains is of the order of their dimensions, it is necessary to take into account the finite size of the particles. In this paper, we study the propagation of surface plasmons in a chain of prolate metal spheroids, taking into account their finite size.
Since dimensions of the nanospheroids included in the chain are much smaller than the light wavelength, the potentials (and, consequently, the field strengths) can be sought in the quasi-static approximation. Expressions are obtained for the field strengths of a prolate spheroid and a point dipole in the case of equality of their dipole moments. It has been found that at small distances from spheroids, these fields
differ significantly (the field of a point dipole is greater than the field of a nanospheroid). Consequently, the field acting on the particle from neighboring spheroids will be smaller, which means that when solving the problem, only the influence of nearest neighbors can be taken into account. Therefore, the dispersion law is studied in the indicated approximation, which makes it possible to obtain the
frequency dependence of the plasmon propagation length. An analysis of the calculation results shows that in the case under consideration, the plasmon free propagation length is longer than in a chain of
spherical particles and oblate spheroids, but shorter than one obtained from calculations using the point dipole approximation.
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Maksym Maniuk |
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H3-AK1142 |
Plasmon resonance in a square lattice of metal nanodisks on a dielectric substrate Nazar Pavlyshche1, Andrii Korotun1,2, Valery Kurbatsky1 1National University "Zaporizhzhia Politechnic", Ukraine As is known, the enhancement of absorption at the frequencies of surface plasmon resonance (SPR) in the lattice of metal nanodisks located on a dielectric substrate can be used to increase
significantly the efficiency of solar cells. Therefore, determining the dependence of SPR frequencies in such a structure on the size and
material of metal nanodisks, as well as on the lattice period, is an urgent task. The size dependences for the frequencies of the transverse SPR can be
found from the condition the denominator of the expression for the lattice polarizability to be equal zero.
In turn, the components of the nanodisk polarizability tensor are determined using the representation by an equivalent spheroid, and in this case, an oblate spheroid will be equivalent [1]. Within the framework of this representation, a dimensional parameter, the effective aspect ratio, is introduced, which makes it possible to replace the study of optical properties of the disk with the study of
the properties of the equivalent oblate spheroid.
The calculations were carried out for lattices of nanodisks of different sizes made of different metals. It has been established that with an increase in the effective aspect ratio, the frequency of the
transverse PPR decreases. In this case, the SPR frequencies decrease in the series of metals Ag → Cu → Au, since the frequency of bulk plasmons for these metals decreases in the same order. It should also
be noted that the frequency of the transverse SPR in the case of latticies of disks with the same dimensions does not depend on the lattice period. Thus, the lattice plasmon resonance can be controlled
by changing material and size of the disk.
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Nazar Pavlyshche |
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H3-YV1623 |
Intrinsic role of Cu⁺ and In³⁺ cations in the nature of ferrielectric ordering in CuInP₂S₆ ferroics Ruslan Yevych, Vitalii Liubachko, Yulian Vysochanskii Institute for Solid State Physics and Chemistry, Uzhhorod National University, Ukraine 2D CuInP₂S₆ ferroics are one of the most representative materials because of their room-temperature ferroelectricity. The spontaneous ordering of electric dipoles below Tc ≈ 312 K creates macroscopic polarization that may be changed by an external electric field. In condensed matter physics, van der Waals layered materials have emerged as a potential study area. Furthermore, their out-of-plane polarization is more suitable for nonvolatile high-speed memory and heterostructure-based nanoelectronics [1].
The QAO model [2] was used to estimate the contribution of copper and indium cations to the origin of ferrielectricity in CuInP₂S₆ crystals. Such a model considers phonon-like bosonic excitations to describe the temperature dependence of the spatial distribution of Cu⁺ and In³⁺ cations. These results were compared with the analysis of the mean-field approach [3] and with calorimetric studies [4], which allowed us to clarify the dipole ordering of the CuInP₂S₆ crystal.
By the QAO model, it was found that In³⁺ cations play a decisive role in the character of polar ordering which is determined by the energy of side wells with respect to the central well of their local potential. At normal and for positive pressures, the first-order transition occurs, which is determined by the higher energy of side wells with respect to the central well of the local potential for In³⁺. At increasing negative compression, the named side wells are stabilized and ferrielectric transition can evolve to the second order.
The peculiarities of polarization switching in different regions of the CuInP₂S₆ temperature-pressure phase diagram are studied and contributions of copper and indium cationic sublattices into polarization hysteresis loops are determined. The multiple polarization states appear as single, double, and triple hysteresis loops. The genesis of the triple P-E loop, as the sum of contributions from Cu⁺ ordering and In³⁺ shifting under electric field E was analyzed in detail.
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Yulian Vysochanskii |
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H3-AP2206 |
Atomic-scale modeling of the formation mechanism of nanocrystalline nucleі of SiC nanofibers from methyltrichlorosilane molecules Peter Sylenko, Alex Pokropivny, Denis Andrushchenko, Yuriy Solonin I M Frantsevich Institute for Problems of Materials Science of NASU, Kyiv, Ukraine For the first time, a model was built using quantum chemistry method (RHF/STO-3G) and the mechanisms of sequential formation of nanocrystalline nuclei of silicon carbide nanofibers were proposed [1-5]. Two types of reaction with methyltrichlorosilane molecules were obtained, namely, when chlorine atoms of one molecule react with a hydrogen atom of another, and when three chlorine atoms of a methyltrichlorosilane molecule react with three hydrogen atoms of a cluster. It was the simulation of such a reaction with the output of three molecules of HCl that makes it possible to simulate a SiC nanocrystalline nucleus of 1 nm in size. The infrared spectra of the clusters were calculated, which confirm the formation of a crystal lattice in the reaction products.
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Alex Pokropivny |
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H3-AP1504 |
Supercritical fluid synthesis of nanocrystalline c-BN and other BN structures from graphite-like boron nitride Alex Pokropivny1, Sergey Maloshtan2, Anatoly Smolyar2, Peter Sylenko1, Yurii Solonin1 1I M Frantsevich Institute for Problems of Materials Science of NASU, Ukraine Cubic boron nitride (c-BN) is known to be the one of the best industrial abrasive and cutting materials, combining wear resistance, high hardness and thermal stability. It is widely used in
electronics due to chemical and mechanical stability, high electrical insulating properties, optical
transparency etc. Supercritical fluid synthesis of c-BN and other dense, intermediate, soft and amorphous BN phases has been studied at pressures 50 — 200 MPa and temperature ~1000 0K from h-BN and t-BN as precursors and H2O and N2 as fluids. According to the results of electron and X-ray diffractions, Fourier-transform infrared spectroscopy and hardness measurements, c-BN phase is proved to be the main synthesized phase with the level of transformation at least 20 %. Two different mechanisms of c-BN nanocrystals formation are proposed. Hardness values of synthesized crystals fill out all scale of
hardness: ultrasoft, soft, normal and hard, characterizing several unconventional phases of boron nitride, including extradiamond E-BN phase.
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Sergey Maloshtan |
Metals and Alloys_program_list
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Oral Session |
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H3-KK6320 |
Phase diagram of the Al–Ti–Cr system Kostyantyn Korniyenko1, Konstantin Meleshevich1, Anatoliy Samelyuk1, Viktor Sobolev2, Lyudmila Kriklya1 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Alloys of ternary aluminium systems with titanium and d metals of the VI-VIII groups are promising for practical application in various fields of modern technology. Addition of a third alloying element, such as chromium, can improve the low temperature ductility and the oxidation resistance. To develop high-temperature structural and functional materials based on the titanium aluminides alloyed with chromium, an understanding of the phase equilibria in this system is essential.
The alloys of the Al–Ti–Cr system of 25 compositions are prepared from components Al, Ti and Cr (purity of 99.995%, 99.8% and 99.93%, respectively) by arc melting. The alloys are investigated in as-cast and annealed at subsolidus temperatures states by optical microscopy, scanning electron microscopy, electron probe microanalysis, differential thermal analysis, and X-ray diffraction techniques.
Phase equilibria in the Al-Ti-Cr system in the range of 40-100 at.% Al during solidification are represented in this work by specified solidus and liquidus surfaces, a melting diagram as their compilation, a Scheil diagram for solidification as well as isopleths at 50, 60 and 70 at.% Al. Continuous series of solid solutions between betaTi and chromium, solid solutions based on alfaTi, TiAl, Ti2+xAl5-x, TiAl3 (high- and room-temperature modifications), Cr5Al8 (gamma3, gamma2 and gamma1 phases), CrAl4, Cr2Al11, CrAl7 binary compounds and the ternary compound tau take part in phase equilibria. Thirteen invariant four-phase reactions (9 – liquid transition, 3 – peritectic, 1 – eutectic) and three invariant three-phase (two peritectic and one eutectic maxima on monovariant curves) reactions involving liquid take place in the system. Isopleths at 50, 60 and 70 at.% Al demonstrate peculiarities of the phase diagram.
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Kostyantyn Korniyenko |
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H3-YP1531 |
Microstructure and thermophysical properties of low-temperature high-entropy alloys Yuriy Plevachuk1,2, Lyubov Romaka1, Irena Janotova2, Peter Svec2, Rada Novakovic3, Viktor Poverzhuk1 1Ivan Franko National University of Lviv, Ukraine The concept of multicomponent high-entropy alloys is known [1, 2], according to which high entropy of mixing can stabilize the formation of solid solutions (simple crystal structure of bcc, fcc) during solidification. Stabilization of the solid solution and prevention of the formation of intermetallic phases during solidification is provided by the high entropy of mixing in the solid and liquid states. High-entropy alloys have increased strength, high hardness, thermal stability in combination with good resistance to oxidation and corrosion. These properties allow to expand significantly the scope of these alloys. The high-entropy alloys must contain 3 or more elements (e.g., CuBiSnInPb, CuBiSnGaPb) in more or less equal proportions.
In this work, the viscosity, electrical conductivity and thermoelectric power of binary Cu–Bi, Cu–Ga, Cu–Pb, Cu–Sn, Pb–Sn, Pb–Bi, Bi–Sn and multicomponent Cu–Bi–Sn, Cu–Bi–Sn–In, Cu–Bi–Sn–In–Pb, Cu–Bi–Sn–Ga–Pb alloys of equiatomic concentrations, which are the sub-systems and components of model low-temperature multicomponent high-entropy alloys, have been studied experimentally in a wide temperature range including liquid and solid states. Based on the obtained results, the activation energy of the viscous flow and the entropy of mixing were calculated. The lack of the surface tension data of the above- mentioned alloys is compensated by the model predicted values. The negative values of the entropy of mixing suggest the structural ordering in the system.
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Yuriy Plevachuk |
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H3-KK1558 |
Solidus surface of the Hf–Rh–Ir system Lyudmila Kriklya1, Kostyantyn Korniyenko1, Vasyl’ Petyukh1, Irina Tikhonova1, Anatoliy Samelyuk1, Viktor Sobolev2, Petro Levchenko1 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Alloys of hafnium with refractory metals of the platinum group (rhodium or iridium) are regarded as perspective materials for a number of applications, in particular, as thermal barrier coatings for details of gas turbines and aerospace vehicles, and as cathodes for electrocatalytic hydrogen production. To develop new perspective functional materials based on the Hf-Rh-Ir alloys, an understanding of the phase equilibria is essential, but there were no available literature information about this.
The alloys of the Hf-Rh-Ir system of 16 compositions are prepared from components Hf, Rh and Ir (purity of 99.98%, 99.97% and 99.97%, respectively) by arc melting. The alloys are investigated in as-cast and annealed at subsolidus temperatures (20-50 °C below melting beginning temperatures) states using optical and scanning electron microscopies, electron probe microanalysis, differential thermal analysis, X-ray diffraction and melting points beginning measurements (Pirani-Althertum technique).
For the first time it was established that solid solution based on betaHf, a continuous series of solid solutions between isostructural (Cu type) components iridium and rhodium, isostructural compounds Hf2Rh and Hf2Ir (Ti2Ni type), high-temperature modifications of HfRh and HfIr (CsCl type), HfRh3 and HfIr3 (AuCu3 type), as well as solid solutions based on the compounds Hf5Ir3 and Hf3Rh5 take part in phase equilibria. Solidus surface of this system is formed by seven single-phase surfaces corresponding to solid solutions based on components and above-mentioned compounds, eight tie-line surfaces limiting the two-phase volumes, and two isothermal planes corresponding to invariant four-phase equilibria with participation of a liquid phase (at 1958 °С and 1655 °С).
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Kostyantyn Korniyenko |
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H3-PA2117 |
Application of CALPHAD method for predicting of concentration range of amorphization of transition metals melts Pavel Agraval1, Mikhail Turchanin1, Liya Dreval1,2, Anna Vodopyanova1 1Donbas State Engineering Academy, Ukraine Metallic glasses are attractive due to a set of unique properties, such as mechanical, magnetic, chemical, etc. At present, information about amorphous alloys is available for individual point compositions in the form of data on conditions of production, structure, mechanical and some other physical properties. However, it is often necessary to search for a new alloy in a wider concentration region.
Early, the efficiency of the CALPHAD (Calculation of Phase Diagrams) method to a targeted search for compositions of amorphous alloys has been shown. The method for predicting of amorphization ranges is based on the calculation of diagrams of metastable phase transformations between supercooled melts and boundary solid solutions. Within the framework of the CALPHAD method, the model parameters for thermodynamic properties of liquid alloys and boundary solid solutions were summarized in self-consistent database for the multicomponent Co–Cu–Fe–Ni–Ti–Zr–Hf system. Such database for the multicomponent system is based on a common set of model parameters for boundary binary and ternary systems.
In this report the predicted ranges of amorphization for the quaternary Cu–Ni–Ti–Zr, Cu–Ni–Ti–Hf, and Fe–Ni–Ti–Hf systems are presented on concentration tetrahedrons. For the quinary Fe–Cu–Ni–Ti–Zr, Fe–Cu–Ni–Ti–Hf, and Cu–Ni–Ti–Zr–Hf systems the composition ranges are predicted along sections from four-component equiatomic alloys to pure metals.
It was determined that the predicted composition ranges of amorphszation correspond to a certain total concentration of metals, which are donors (Ti, Zr, Hf) and acceptors (Fe, Ni, Cu) of electrons in the melt. For glass-forming melts of transition metals such a factor is the simultaneous fulfillment of the conditions of xTi+xZr+xHf > 0.2 and xFe+xNi+xCu > 0.2. This factor indicates the important role of the donor-acceptor interaction between components of the glass-forming liquid alloys and its influence on their ability to amorphization.
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Pavel Agraval |
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H3-KP1437 |
Thermokinetics of Recrystallization of Copper Compacts Viktor Solntsev, Gennady Bagluk, Tetiana Solntseva, Kostiantyn Petrash Frantsevich Institute for Problems of Materials Science, Ukraine The mechanisms of copper recrystallization processes, as well as other metals and alloys, are of particular interest in connection with the problems of forming the structure and properties. The dynamics of thermal processes during recrystallization significantly affects the technological properties and the formation of a spatially organized structure.
The study of the thermokinetics of recrystallization of copper compacts was carried out on a solar plant with unilateral radiant heating from the side of the end face of cylindrical samples. To obtain compacts, electrolytic copper powder was used. The samples were pressed in a cylindrical mold with a diameter of 10 mm. Chromel-alumel thermocouples were installed in holes in the depth of the sample and placed lengthwise with a step of 4 mm from one another. The change in the temperature of the reaction system was recorded using a high-speed computerized signal recording system.
The recrystallization process can be viewed as a first order reaction, i.e. the transition from the deformed state to the annealed state with an ideal lattice and is accompanied by a thermal effect. Several stages of recrystallization were found, which corresponds to the known data, but the appearance of traveling thermal waves is observed. By analogy with first-order reactions in the high-temperature synthesis of intermetallic compounds, the appearance of various types of wave processes has been shown. Traveling waves can appear in the system. This can lead to thermal interference and, as a result, there is localization of thermal energy and a sharp increase in temperature in certain areas of the wires deformed during switching, and their ignition. The experimentally observed values of temperature bursts indicate the occurrence of combustion processes in insulating materials. Thus, it is possible to explain the cause of accidents observed during the operation of complex mechanisms with a large number of electrical connections.
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Tetiana Solntseva |
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H3-OZ1653 |
Role of hydrogen in strain aging of ferritic/pearlitic low alloy steel under long-term operation Olha Zvirko, Hryhoriy Nykyforchyn, Oleksandr Tsyrulnyk, Myroslava Hredil, Oleh Venhryniuk, Halyna Krechkovska, Oleksandra Student Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine Long-term operation of structural steels often results in a significant deterioration of initial mechanical properties determining their serviceability [1]. Two main stages of operational degradation of structural steels are commonly considered [2]: strain aging and development of dissipated damages, resulted in metal embrittlement. In the paper, the influence of hydrogen on embrittlement of ferritic/pearlitic low alloy steel on the stage of strain aging was analysed. It is known that hydrogen charging of steels is accompanied by an increase in internal stresses. In this case, it was assumed that plastic deformation will be localized in sites with the highest hydrogen concentration, and strain aging will occur in these locations during subsequent heating of steel after hydrogen charging. The Fe-0.17C-1.5Mn-0.5Si low alloy steel in the as-delivered state and after 36 years of operation was investigated. The specimens were subjected to electrolytic hydrogen charging. Then they were heated to 250 °C and held for 1 hour. Such a procedure enables inducing strain aging in local plastically deformed locations and desorbing hydrogen. The results showed that the steel subjected to the procedure of combining preliminary hydrogen charging with heating was characterized by a significant decrease in fracture toughness and resistance to stress corrosion cracking. The effect was more significant for the long-term operated steel. Embrittlement of the treated steel was confirmed by fractographic analysis of specimens tested for stress corrosion cracking, which revealed intergranular fracture. Such a behaviour of the steel was associated with strain aging of the hydrogen pre-charged metal. It was indirectly shown that hydrogen charging of steels can cause embrittlement by the strain aging mechanism in the dominant sites of hydrogen transport, namely, the grain boundaries.
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Olha Zvirko |
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H3-HK2135 |
Visualization of damage to heat-resistant steel after long-term operation on the main steam pipeline for fractographic signs of its destruction Halyna Krechkovska1,2, Oleksandra Student1, Ivan Tsybailo1 1Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine The influence of operational factors contributes to the occurrence of damage in elements of thermal power equipment with their subsequent fracture. Fractographic analysis has become widely used to assess the technical condition of operated steels, in particular to find out the reasons of the destruction of structural elements. The identified fractographic features allow to establish the current state of thermal power elements.
The low-alloy heat-resistant steel 15Kh1M1F in the initial state and after the long-term operation in main steam pipelines of TPP were studied. To assess the actual state of the operated metal, the following characteristics were used: impact toughness, fracture toughness, fatigue crack growth resistance. Metallographic and fractographic peculiarities of steel were evaluated using SEM.
The quantitative structural indicators that determine the mechanical properties of the steel long-term operated on the steam pipelines include the sizes of grains and carbides in its structure, which increase with more shutdowns of power units. The fractographic sign of cohesion weakening between adjacent grains in operated heat-resistant steel is fragments of intergranular fracture on the fracture surfaces steam pipelines and also on the fracture surfaces of steel specimens after impact and fatigue testing. These intergranular fragments are considered the key sign of steel’s degradation indicating structural changes in it, namely, the precipitation and coagulation of carbides along the grain boundaries, their separation from the matrix to form pores, their further merging and thus initiation of intergranular cracks. It is proposed to use the area of intergranular fragments per unit area of the fracture surface as a quantitative fractographic indicator of the change in its technical condition due to degradation. This fractographic indicator of the metal state is consistent with the mechanical characteristic of resistance to brittle fracture.
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Halyna Krechkovska |
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H3-SV0280 |
Thermodynamic properties of melts Bi-Pr of system Volodymyr Shevchuk, Volodymyr Kudin, Nataliya Podoprigora, Valentina Sudavtsova I.M Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Alloys and compounds of many systems of Bi with d- and f-elements exhibit thermoelectric and magnetic properties. In order to obtain such materials, it is necessary to know their phase diagrams and thermodynamic properties of various phases, especially liquid, because most of them are obtained by melting. The thermodynamic properties of diluted melts with respect to Pr have been studied by the EMF method [1]. According to these data, the first partial enthalpy of mixing is –259.6±2.5 kJ/mol at 1000 K. The enthalpies of formation of intermediate phases Pr4Bi3 and PrBi determined by the method of calorimetry are exothermic (-93.8±2.1 and –100.1±2.1 kJ/mol). The thermodynamic properties of melts of the Bi-Pr system were first investigated by the method of calorimetry at 0 < xPr < 0.3 and T =1310±2 K in this paper. It was established that the first partial enthalpy of mixing of bismuth is -400±28 kJ/mol, which correlates with a similar value for Pr determined by the EMF method. Approximation of our experimental data, taking into account the fact that at хBi=1 ΔН=0, made it possible to calculate the integral and partial enthalpies of mixing in the entire range of concentrations (the minimum integral enthalpy of mixing is −75±12 at xPr = 0.65 at 1310±2 K) . This is consistent with the fact that ΔfН of Pr4Bi3and PrBi compounds is larger in absolute value, as is characteristic of melts with a strong energy of interaction between particles of different atoms. In order to expand the information about the thermodynamic properties of all phases of the Bi-Pr system, we calculated and optimized these parameters using the ideal associated solution model. The activity of the components shows very large negative deviations from ideal solutions. The maximum molar fractions of PrBi and Pr2Bi associates are 0.92 and 0.7, respectively. This confirms high energy of interaction between the heterogeneous atoms at these concentrations and predominant role of associates in them.
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Volodymyr Shevchuk |
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H3-SV0561 |
Thermodynamic properties of melts of Mg–In and Mg–In–Yb systems Dudnik Anton, Volodymyr Kudin, Larysa Romanova, Valentina Sudavtsova I.M Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Data on the thermodynamic properties of various phases and, in particular, the liquid phase, are necessary for the scientifically based development of methods for obtaining the specified materials. Therefore, the purpose of this work are to study by the method of calorimetry the enthalpies of mixing of melts of Mg–In systems in the range of compositions 0 < xMg <0.3 and at Т=961±1K, as well as Mg–In–Yb for the section 1:1 at Т=1281±1K. The thermodynamic properties of the liquid phase of the Mg–In system have currently been studied by various methods and optimized in [1]. A comparison of ΔН determined by us and optimized showed that they agree with each other within the experimental error (ΔНmin=-6.7 and -7.7±0.5 kJ/mol). For the melts of the Mg–In–Yb system in the studied section up to xYb<0.3, it was established that the first partial enthalpy of mixing of ytterbium is -100±8, and ΔНmin= -27.2kJ/mol. This indicates on the formation of ternary associates with a rather large energy of interaction between atoms of different names. The thermodynamic properties of the liquid phases of the Mg–Yb and In–Yb systems are now known. Their ΔHmin=-4.3 at 1016K and –36.5±1.0 kJ/mol at 1350 K, respectively. In recent years, thermodynamic properties of melts of ternary systems have been calculated from similar data for binary boundary subsystems according to the Redlich-Kister-Mujianu model, when the data for the latter are known. We estimated the thermodynamic properties of melts of the Mg–In–Yb system according to this model. According to our calculations, it was established that ΔНmin=-36.5±1.0 kJ/mol at xYb=0.5 of the In–Yb subsystem. ΔG, ΔS of these melts were calculated according to the same model. It was established that ΔGmin=–28.5 kJ/mol, and ΔSmin=–7.9 J/mol·K, the minimums of which also fall on the same limiting subsystem, i.e., the main contribution to the interaction energy between different atoms of melts of the Mg–In–Yb system the contribution of In–Yb subsystem.
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Dudnik Anton |
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Poster session Important.session is online-only and include 5 min presentation in the common conference room and 1 hour of discussion in individual rooms (Zoom) |
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H3-AB1458 |
Surface hardening of Ti6Al4V alloy using high-frequency mechanical impacts Svitlana Voloshko1, Andrii Burmak1, Bogdan Mordyuk1,2, Taras Krasovskyi3, Nataliya Franchik1, Myhailo Vasylyev2 1National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” A comparison of the effects of high-frequency hardening by balls (SMAT) and local high-frequency mechanical impact (HFMI) treatment by an impact element on the mi-cromechanical characteristics and microstructure-phase state of the surface of the Ti6Al4V (VT6) alloy is carried out. The SMAT processing of the sample surface was carried out in the air for 30–240 s with steel balls of 2 mm in diameter, the movement of which was induced by an ultrasonic sonotrode oscillating at a frequency of ~20 kHz. The results were compared with the HFMI processing by cylindrical steel striker of 5 mm in diameter under comparable time regimes. The mechanical characteristics were determined based on the instrumental indentation data, and the microstructure parameters and the presence of the oxide phases on the surface were determined by X-ray diffraction analysis. The features of the microhardness changes and XRD based data regarding the macrostresses, crystallite size, and microstructure-phase state after high-frequency impact treatments of various ultrasonic excitations were established.
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Andrii Burmak |
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H3-ST1410 |
Bioresorbable powder materials based on Mg-Mn-Zn Serhii Teslia, Tetiana Soloviova, Mykhailo Vterkovskyi, Vitalii Sheremet, Petro Loboda Igor Sikorsky Kyiv Polytechnic Institute, Ukraine Bioresorbable materials are a breakthrough solution in biomaterials science for different orthopedic surgeries. Due to controlled resorbed, the material is removed from the body after the overgrowth of the bone tissue. Powder magnesium alloys have found wide applications for creating bioresorbable fixing pins. Pure magnesium dissolves quickly and forms a large amount of hydrogen, which negatively affects the human body. To increase corrosion resistance, alloying elements, usually rare earth materials, are added to magnesium. The aim of the work was to study the processes of mixing and consolidation of Mg-Mn-Zn. The initial powders (Mg-1 wt. % Zn, Mg-1 wt. % Mn, Mg-1 wt. %; Mn-1 wt. % Zn) were mixed in a shaker mixer for 10, 15, 20, and 25 hours without the addition of mixing agents. The quality of mixing was assessed using microstructural analysis and EDS elements mapping. Densification was carried out by uniaxial and cold isostatic pressing, for 200-600 MPa. Green samples were sintered at 600 °C for 2 h in an argon atmosphere. In the first stage of mixing, an increase in the quality of mixing is observed. But an increase in time above 20 h leads to the formation of conglomerates, which reduces the uniformity of the alloying elements distribution. Due to the high plasticity of magnesium, even at 400 MPa, it is possible to obtain almost 100% material density, both by uniaxial and isostatic pressing. The densification method significantly affects the final microstructure of the alloys. When uniaxial pressing was used, the pores have an angular shape with an average size of 20 µm. After CIP, there are practically no pores in the structure of the material; single pores have a spherical shape of less than 5 µm. It was found that increasing the mixing time does not linearly change the uniformity of the alloying distribution. The use of CIP for densification of magnesium alloy powders is more preferable as it provides low porosity and alloying uniformity by volume.
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Serhii Teslia |
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H3-NU1736 |
The thermochemical properties of ternary Ag–Eu-Sn liquid alloys Natalia Usenko1, Michael Ivanov2, Natalia Kotova1 1Taras Shevchenko National University, Department of Chemistry, Kyiv, Ukraine Ternary alloys of the Ag–Sn–Eu system may be of practical interest for several reasons. For example, ternary alloys of europium with silver and p-metal have interesting magnetic properties. Besides, binary and ternary alloys containing tin and silver are widely used as lead-free solders and the presence of a rare-earth metal in solders refines their microstructure, melting behaviour and mechanical properties. The lanthanides also improve the corrosion properties of such solders, reducing their corrosion rate. So, thermodynamic data for the Ag–Sn–Eu system may be useful, giving the possibility of calculating phase equilibria to find the compositions with the best technological efficiency. The present investigation is a prolongation of a series of systematic studies of ternary alloys of the transition metal–rare-earth metal–p-metal family. The enthalpies of mixing in liquid alloys of the ternary Ag–Sn–Eu system were determined over a wide range of concentrations by means of isoperibolic calorimetry in the temperature range from 1313 to 1373 K. The partial enthalpies of each component of the ternary system were measured along the following sections: the partial enthalpy of silver along the section with xSn/xEu = 0.72/0.28 up to silver content of about xAg = 0.2 at 1373 K; the partial enthalpies of tin along three sections (xAg/xEu = 0.31/0.69, 0.50/0.50 and 0.70/0.30) up to xSn = 0.35 at 1373 K; the partial enthalpy of europium along the section xAg/xSn = 0.50/0.50 up to xEu = 0.25 at 1313 K. The enthalpies of mixing in the liquid Ag–Sn–Eu alloys show exothermic effects, being more pronounced in the vicinity of the Sn–Eu binary constituent. The minimum value of the integral enthalpy of about –60 kJ/ mol is observed in the composition region of the congruently melting Eu2Sn phase.
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Natalia Usenko |
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H3-OM1256 |
Properties of nickel powders obtained by reduction in moving layers Olena Makarenko, Petro Radchenko, Olha Hetman, Tetyana Babutina, Anatolii Samelyuk Frantsevich Institute for Problems of Materials Science of NASU, Ukraine Nickel powders are usually produced by hydrogen reduction of nickel oxide in stationary furnaces in a fixed layer. In this case, it is necessary to ensure the rapid removal of water vapor from the reduction zone by increasing hydrogen consumption. A promising method for obtaining nickel powders is the reduction of nickel oxide in hydrogen in moving layers in a rotary furnace. The movement of powder layers during reduction ensures continuous contact of oxide particles with hydrogen, rapid removal of water vapor from the reaction zone, and establishment of a reduction regime close to kinetic. The aim of this work was to determine the properties of nickel powders obtained by reduction in a rotary furnace.
Nickel oxide was obtained by decomposition of basic nickel carbonates at 550°C for 1 h. The reduction of nickel oxide with hydrogen was carried out at 500 and 600°C for 2 h. The dispersity of the powders was estimated from the specific surface determined by the thermal desorption of nitrogen. The oxygen content in nickel powders was determined by gas chromatography. The morphology and particle size of the nickel powders were explored with a scanning electron microscope.
Nickel powders were produced from nickel oxide with a specific surface area of 25 m2/g. Nickel metal powders are highly porous agglomerates consisting of submicron nickel particles. The sizes of agglomerates are in the range from 5 to 125 microns. The powders have a high specific surface were 5,8 and 3,5 m2/g at reduction temperatures of 500 and 600 °C, respectively. The nickel agglomerates formed in the rotating chamber have a smooth rounded shape. The bulk density of the Ni powders was 1,3 g/cm3, the oxygen content was 0,06%. Nickel powders are actively compacted during sintering. The compaction factor of samples at a sintering at 1250 °C for 20 min depends on the specific surface of the powders and is 0.8 and 0.6 for powders with a specific surface of 5,8 and 3,5 m2/g, respectively.
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Olena Makarenko |
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H3-PK2110 |
Experimental bench tests on the corrosion resistance of construction materials and environmental safety for the cooling system of a nuclear power plant with biocides water treatment Pavlo Kuznietsov1,2, Olga Biedunkova1 1National University of Water and Environmental Engineering, Ukraine Biological pollution creates significant obstacles in the operation of power plants' technical water supply cooling systems (SCS). To minimize biological pollution, methods of corrective treatment with biocides are implemented. While these biocides effectively prevent fouling of the cooling system, they can also adversely affect the environment and structural materials. By evaluating structural materials' corrosion resistance and biocides' environmental safety for the cooling water during biocide treatment, any potential issues can be identified and addressed before they become a safety or operational concern. The paper presents the results of bench tests of the corrosion resistance of structural materials SCS, corrosion aggressiveness of the biocides: sodium hypochlorite NaClO and 2, 2-dibromo-3-nitriloropionamide (DBNPA), and the results of measurements of the concentration of biocides and their decomposition products to assess compliance with environmental standards when discharging return water when applying from biocides treatment. The cooling water SCS of the Rivne NPP (Nuclear Power Plant) was chosen as the research object. Bench corrosion tests were carried out using samples of corrosion indicators from materials: steels Ст20, 08Х18Н10Т; copper alloy МНЖ-5-1 and aluminum, which are defined as analogs of structural materials of the technical water supply system of the Rivne NPP. The conditions of operation of the technical water SCS of the Rivne NPP were simulated on the test bench, and corrosion rate measurement was carried out by the gravimetric method.
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Olga Biedunkova |
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H3-IV1159 |
Structural sensitivity of the wear resistance of Armco-iron at friction by quasistatic and dynamic loading Konstantin Grinkevych, Yurii Podrezov, Alex Golubenko, Igor Voskoboynik, Nick Iefimov Institute for Problems in Materials Science NASU of І.М.Fratsevich, Ukraine On the example of Armco-Fe, the structural sensitivity of wear resistance both of the quasistatic and dynamic friction loading was studied. Armco-Fe samples with different grain sizes, from ~21 µm to ~560 µm, were obtained. Tribological properties and microhardness were studied. Wear tests were carried out on the tribodynamic complex (ATKD). Reciprocating sliding movement of an indentor from 52100 steel ball vs the polish surface of flat specimens was carried out. Microhardness was determined on PMT-3 by Vickers indenter under load P=0.5 N.
The structural sensitivity of the hardness (H) and wear resistance (W) under static loading shows three sections. In the area of small grains, where the size of the indent or contact spot together with the plastic zone around them turns out to be larger than the grain size, the experimental dependences follow the Hall-Petch law: W, H~d⁻¹⁄².
In the region of large grains, where the plastic zone under the indent fits into one grain, there is no sensitivity to the grain size. The anomalous nonmonotonic dependence located in the middle area, where the grain size is comparable to the size of the plastic zone. It can be explained by the interaction of dislocations in the plastic zone with the grain boundaries, which either limit the movement of dislocations, forming clusters, or on the contrast, accelerate the process of their propagation due to the triggering of Frank-Reed sources near the boundaries.
In case dynamic loading the wear resistance demonstrates similar structural sensitivity, but the relative influence of the grain size is much smaller. In this instance the intensive deformation processes took place in the subsurface layer with the formation of dislocation substructure. Such effect is much stronger on the wear resistance than the effect of the boundaries.
The likeness of structural sensitivity of the studied mechanical characteristics testifies the uniform deformation mechanisms determining the grain size effect on H and W.
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Konstantin Grinkevych |
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H3-NK1342 |
The enthalpies of mixing of ternary Al–Ce–Co liquid alloys Natalia Kotova1, Natalia Usenko1, Michael Ivanov2 1Taras Shevchenko National University, Department of Chemistry, Ukraine For aluminium-rich alloys of the Al–Ce–Co ternary system, amorphous alloys have been obtained, which are characterized by high specific strength and high resistance to corrosion. Persistent efforts to synthesize bulk Al-rich amorphous alloys have been made for over a decade. The process of metallic glass formation and the prediction of new glass compositions are ongoing areas of intensive research. One of the necessary conditions for the successful prediction of such compositions for each glass-forming system is the existence of a thermodynamic description of the liquid phase, which is directly involved in the formation of amorphous metallic glass. The experimental data on enthalpies of the formation of liquid alloys are an important part of obtaining such a description. The present investigation is a prolongation of a series of systematic studies of ternary alloys of the transition metal–rare-earth metal–p-metal family. The enthalpies of mixing in liquid alloys of the ternary Al–Ce–Co system were determined over a wide range of concentrations by means of isoperibolic calorimetry at 1823 K. The partial enthalpies of each component of the ternary system were measured along the following sections: the partial enthalpies of aluminium along the sections with xCe/xCo = 0.77/0.23 and 0.35/0.65 up to aluminium content of about xAl = 0.2; the partial enthalpy of cerium along the section xAl/xCo = 0.76/0.24 up to xCe = 0.3; the partial enthalpy of cobalt along the section xCe/xAl = 0.70/0.30 up to xCo = 0.22. The enthalpies of mixing in the liquid Al–Ce–Co alloys show exothermic effects, being more pronounced in the vicinity of the Al–Ce binary constituent. The minimum value of the integral enthalpy of about –50 kJ·mol–1 is observed in the composition region of the congruently melting at high temperature Al2Ce phase.
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Natalia Kotova |
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H3-VM1404 |
The Iron-Carbon System. Eutectic crystallization Involving Hyper-cementite Carbide. Vladyslav Mazur Igor Sikorsky Kiev Polytechnic Institute, Ukraine White cast irons are successfully used in foundry production for parts that operate under static conditions. The brittle cementite matrix limits its use in impact applications. This relatively inexpensive material can be used under shock loads if we invert the eutectic constituent. Thus, the purpose of this work is to develop the theory and technology of inverted eutectics crystallization. The methods used include light metallography with a Jenaphot 2000 (Carl Zeiss, Jena, Germany) and differential scanning calorimetry with a STA 449C “Jupiter” (Netzsch Gerätebau GmbH, Germany). A simple technology of thermal cyclic processing of the melt has been developed in order to generate significant super-cooling, which causes the formation of inverted plate-like eutectics with a matrix of transformed austenite and carbide reinforcing phases. The features of the kinetics of nucleation and growth of inverted plate-like eutectics based on metastable carbide (Fe7C3+γ) (in microscopic and thermal (DSC) imaging) have been established. On the basis of the results of experiments, the schematic diagram of the metastable phase equilibrium in the subsystem Fe-Fe3C-Fe7C3 has been provided. With the help of the diagram, it is possible to explain without contradiction all the phase transformation in a subsystem. This work lays the foundation for the theory and technology of a new cheap natural composite with a matrix of transformed austenite and Fe7C3 carbide reinforcing phases.
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Vladyslav Mazur |
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H3-OB1142 |
Peculiarities formation of welded joints under the external electromagnetic influence Sergei Maksimov, Olena Berdnikova, Olena Prilipko, Tetiana Alekseenko E.O. Paton Electric Welding Institute National Academy of Sciences of Ukraine Controlling the movement of liquid metal by selecting the parameters of an external electromagnetic effect makes it possible to change the conditions of dynamic equilibrium of the weld pool and, as a result, the formation of a weld.
Magnetic process control has advantages over mechanical control methods, since it is carried out without contact with the welding zone.
The study of processes leading to a decrease in the concentration of defects in metals, recombination of dislocations, polygonization, recrystallization, defect healing, etc., is an urgent task for technologists.
The work aims to investigate the effect of EEW during welding on the microstructure parameters, phase composition, microhardness, strength properties and crack resistance of the metal of welded joints of low-alloy steel.
Microstructure studies were carried out by light, scanning, and transmission electron microscopy. Mathematical modelling was carried out to optimize the research efficiency. The developed computer application implements the idea of sequential calculation of quantities, where the value of the welding current and the current in the inductor is selected by the researcher.
It has been established that the most effective in welding low-alloy steel with EEW is using transverse magnetic fields. This ensured the formation of the most acceptable structure with a uniform level of microhardness both in the weld metal and in the HAZ sections and a noticeable refinement of the structure. The influence of structural factors at the dislocation level on local internal stresses, which determine the deformation localization zones in the structures of the upper and lower bainites in the deposited metal, is analyzed. The conditions for obtaining high-quality welded joints in the welding of low-alloy steels, which ensure their strength and crack resistance, are established.
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Olena Prilipko |
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H3-IF1252 |
Phase transformations in the Ti-Fe-Sn system Iuliia Fartushna, Maryna Bulanova, Kostyantyn Meleshevych, Anatolii Sameliuk, Iryna Tikhonova I.M. Frantsevich Institute for Problems of Materials Science, Ukraine Heusler intermetallic compounds are a class of very promising materials with wide potential applications due to various useful properties. Fe-based Heusler compounds noteworthy magnetic properties and are also considered as highly attractive candidates for thermoelectric materials. The magnetic properties of Fe3Sn compound are also interesting. In addition, ultrafine eutectics with high strength and plasticity are formed in the Ti-Fe-Sn system and in multicomponent systems based on it. Thus, the ternary Ti-Fe-Sn system is of practical and scientific interest.
Bulk metals of Ti-99.98%, Fe-99.9%, Sn-99.9995% were used to produce the ternary alloys. Alloys were prepared by arc-melting under a purified argon atmosphere using a non-consumable tungsten electrode on a water-cooled copper hearth. The as-cast samples were homogenized at 1000°C for 2 months in quartz tubes in a SNOL 7.2/1100 muffle furnace. The as-cast and annealed alloys were then examined by scanning electron microscopy, electron probe microanalysis, differential thermal analysis, and X-ray diffraction analysis.
In present work the phase equilibria in the Ti-Fe-Sn system were studied for the first time upon crystallization and at 1000°C in a whole concentration region. The liquidus and solidus projections, the Scheil diagram and isothermal section at 1000°C were constructed. It is shown that the half-Heusler FeTiSn phase melts congruently, while the Fe2SnTi (full-Heusler) and FeSnTi2 form by peritectic reactions. Only Heusler Fe2SnTi phase has a wide range of homogeneity from 48 to 67 at.% Fe.
Three binary phases Ti5Sn3, Ti6Sn5 and TiFe2 have extended homogeneity ranges in the ternary system. TiFe2 dissolves 13 at.% Sn. The solubility of Fe in Ti6Sn5 was measured to be 21 at.%. Ti5Sn3 dissolves 14 at.% Fe forming an interstitial solid solution, which orders at composition Ti5FeSn3. This ordered phase Ti5FeSn3 has a Hf5CuSn3 type structure.
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Iuliia Fartushna |
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H3-AO1637 |
Molecular dynamics simulation of an early stages of interfacial amorphization in Ni/Ti system Sergii Konorev, Yaroslav Sokur, Ivan Kruhlov, Andrii Orlov National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine NiTi intermetallic alloys are promising for application in biomedicine [1] and microelectromechanical systems (MEMS) [2] due to their pronounced shape-memory effect, high work output, and good corrosion resistance. Though it is known that the growth of the intermetallic phases occurs through the formation of an amorphous phase [3], currently there is a lack of understanding of where this phase starts to form as well as the factors affecting this process. Present work is focused on studying the nucleation kinetics of NiTi amorphization by computer simulations.
To address this goal, we applied computer simulation using molecular dynamics (MD) approach. LAMMPS software and modified embedded-atom method (MEAM) potential for Ni-Ti system [4] were used. The model structure consisted of bi-, four- and six-layered stacks of alternating fcc Ni and hcp Ti (total number of atoms in system was up to 60000). The system was relaxed using energy minimization at simulation temperature followed by the heating to 900 K with exposition up to 105 steps MD (10-9 s) .
It was found that the processes of lattice distortion and nucleation at the interfaces are spontaneous and have a thermally activated nature. The probability of nucleation as well as the time of its formation increased with increasing the heating rate, which is most likely associated with the interfacial stresses arising due to the lattice mismatch and difference in CTE of Ni and Ti more than 1.5 times. At high heating rates (200 К/1000 steps MD), the stresses cannot fully redistribute and relax through the system, thus they act as a driving force for the nucleation. Moreover, the kinetics of nucleation is the higher, the farther from the outer surface the interface is located. It was also revealed that the nucleation onset is affected by the combination of the Ni and Ti crystal faces with different atomic packing density, as well as the number of the interfaces in the model.
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Yaroslav Sokur |
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H3-VT0105 |
Electrochemical studies of the dental implants from titanium and titanium alloys Victor Talash1, Yuliia Rudenko1, Valerii Nespryadko2, Valerii Los2, Maskim Pavlenko3, Valerii V. Los3 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine A lot of metals and alloys are used in the manufacture of dental prostheses (implants). Unfortunately, corrosion processes take place in the oral cavity on the surfaces of dental materials with the formation of products that can have an individual effect on the particular human organism. Determination of the implants’ surface resistance to dissolution in the oral cavity environment (electrolytes) has practical clinical significance.
The implant material composition is a decisive to prevent of it dissolution and complete corrosion protection. Each implant has its own specific corrosion behaviour. To increase the stability of titanium implants and increase the biotolerance and biocompatibility of the implant with the surrounding bone, it is recommended to carry out preliminary anodic polarization.
Electrochemical corrosion studies were performed by potentiodynamic polarization curves method in 3% NaCl solution for investigation of possible anodic dissolution of the implants from titanium (99.99%) and titanium alloys. The platinum counter electrode and Ag/AgCl as the reference were used. The temperature was 310 K for all experiments.
If there are at least two implants of different nature, the potential difference of the galvanic pairs can be 0.2-0.3 V max. The alloy VT-6 (Ti – 89.03%; Al – 6.85%; V – 4.13%) has an insufficient length of the corrosion-resistant interval potentials (0.2 V). This can cause its dissolution products (V and Al ions) to enter the human body, which have a negative effect if the MPC is exceeded.
The obtained data indicate high corrosion resistance of pure titanium and its alloys with Nb and Si. The previous anodic polarization of these implants in the range from a stationary potential to 1 V contributes to the creation of a nanofilm (Ti₂O, TiO and Ti₂O₃, thickness up to 20 nm), which tightly adheres to the base and does not crack during long-term operation, and leads to significantly increase their life time.
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Victor Talash |
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H3-MS0351 |
Features of obtaining high-entropy CoCrFeNiMn1-x alloys by the powder metallurgy method and their mechanical properties. Maria Saviak1, Angel Vicente Escuder2, Elizaveta Klytskina2, Vicente Amigó Borrás2 1Institute for Problems of Material Sciences NAS of Ukraine In the work, a series of high-entropy CoCrFeNiMn(1-x) alloys (where x varies from 0 to 1) was obtained by mixing the initial metal powders in a mixer, followed by compaction of the powders under a pressure of 1000MPa, followed by sintering at 1200-1300С in a vacuum. The formation of high-entropy alloys after sintering is evidenced by X-ray and significant plasticity, which reaches 5.8% during flexural strength tests. It is shown that the processes of consolidation of CoCrFeNiMn(1-x) alloy powders are influenced by both the percentage of manganese and the sintering temperature. Evaporation of alloy components and different diffusion coefficients of alloy components lead to volume growth of samples in the entire range of manganese concentrations (0-20 at%) at temperatures of 500-800C, and the high activation energy of sintering of the CoCrFeNiMn(1-x) alloy does not allow obtaining dense samples even when the temperature of sintering is increased to 1300C. Samples with 5-10at% manganese had the highest density of 86%. Alloys with 5 at.% Mn showed the greatest strength and ductility. The alloy with 10 at.% Mn had the highest modulus of elasticity .
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Maria Saviak |
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H3-OM1330 |
The rational constructional and technological parameters determination method for powder materials forming processes Anatoliy Mikhailov1, Yevgenii Shtefan2, Oleg Mikhailov1 1Institut for Problems of Material Sciences National Academy of Science of Ukraine Problem statement and objective.
One of the perspective methods products manufacturing is the powder materials shape formation processes. The effective deformation schemes design and rational technological powder specimen parameters determination is possible on the base of preliminary computer modeling. So, one of the main problems in the powder metallurgy technologies design is the mathematical and computer modeling methods development for the corresponding products shape formation processes.
Methods
The main research method is based on mathematical modeling of the shape formation processes of dispersed materials in the regime of plastic and elastic-plastic deformation of the solid phase with the use of projection-grid methods and computer technologies. Computational experiments are used for rational technological schemes determination of powder materials forming processes.
Main results and Conclusions
The mathematical model of shape formation processes of structurally inhomogeneous porous materials is developed. On the basis of the generalized model of plastic deformation of powder and porous materials processes and by the finite elements method the technique of rational constructive-technological parameters determination for powder metallurgy technologies is developed.
The practical use of the proposed methodologies made it possible to determine: - the regularities of the different moduli material layers interaction during stamping of bimetallic blanks with an inner cone-shaped surface; - the porosity distribution over the workpiece volume at the final stage of radial extrusion of the bushings with an internal flange; - the effect of powder material decompaction during reverse extrusion of cylindrical products.
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Yevgenii Shtefan |
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H3-OK2018 |
Structure and properties of liquid quenched Al₄CoCrCuFeNi high-entropy alloy Oleksandr Kushnerov, Valerii Bashev, Serhii Ryabtsev Oles Honchar Dnipro National University, Ukraine High-entropy alloys (HEAs) are a new class of metallic materials that have attracted a lot of attention in recent years. Unlike conventional alloys, which are based on one or two dominant elements with minor additions of other elements, HEAs consist of five or more elements in equal or near-equal proportions. This leads to a high configurational entropy of mixing, which can stabilize simple solid solution phases. HEAs have shown excellent strength, ductility, fracture toughness, wear resistance, corrosion resistance and high temperature stability.
Previous research indicates that Al greatly increases the hardness of CoCrCuFeNi base high entropy alloy. This study investigates how the cooling rate influences the structure, phase formation, and microhardness (Hµ) of Al₄CoCrCuFeNi HEA. The films of the investigated HEA were produced by applying the liquid quenching (LQ) technique to the melt that was obtained from remelting the as-cast ingot. The LQ technique involved the rapid cooling of melt drops upon their impact with the internal heat-conducted surface of a fast rotating (~8000 RPM) hollow cylinder. The cooling rate was estimated to be ~1000000 K/s.
An analysis of the X-ray diffraction patterns made it possible to determine that the structure of the as-cast HEA consisted of a B2 phase that had a lattice parameter a=0.2919 nm. When the liquid quenching was performed, the phase composition remained unchanged, while the lattice parameter became a=0.2916 nm. The microhardness of the as-cast HEA was measured to be Hµ=6500 MPa, while the microhardness of the LQ HEA was significantly higher and reached Hµ=9400 MPa. The reason for this difference in microhardness apparently consists in the fact that the LQ Al4CoCrCuFeNi HEA films were far from the equilibrium state and had a microstructure that was characterized by a higher level of microdeformations, dislocation density, and smaller grain sizes, in contrast to the as-cast samples, which were in a more equilibrium state.
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Oleksandr Kushnerov |
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H3-VK1423 |
Wetting of metal substrates with liquid halides Vitalyi Krasovskyy, Nataliia Krasovskaya Frantsevitch Institute for Problems of Materials Science of NASU, Kyiv, Ukraine Many functional metal materials (brazing alloys, amorphous, shape memory alloys) contain chemical active Zr and Ti. The refractory crucibles used for melting such melts do not ensure the complete homogenization of the alloys. The revealed anomalous phenomenon of non-wetting of alkaline earth metal fluorides by melts at high temperatures [1–4], which contain Ti, Zr, solves the specific problem of obtaining inert refractory materials in contact with chemically aggressive melts. The aim of this work is to study the contact interaction in solid metal/liquid halide systems. Wetting of solid Ti, Ni, Cu, Al substrates by liquid LiF, NaF and MgF2 was carried out by the sessile drop method in a vacuum of 1×10 -3 Pa at the melting temperatures of halides. The surface profile of the substrates after interaction with the halide was studied using the optical method on a non-contact interference 3D profilograph. Liquid LiF, NaF, MgF2 wet Ti, Ni, Cu, Al, contact angles are much less than 90 град., adhesion of melts to substrates is high. At the experimental temperature, liquid LiF, NaF and MgF 2 rapidly evaporate. The losses of the Ti-substrate after wetting with fluorides are much greater than the losses of the Ti substrate after annealing at a temperature of 1553 K. The "hole" is formed under a drop of MgF2 . The roughness of the Ti substrate after annealing is 1–4 μm, and the depth of the “hole” is greater than 14 μm. The study of the geometry of the contact boundary in the solid titanium–liquid LiF, NaF, and MgF2 system confirmed the possibility of the formation of gaseous products of the interaction of Ti with F. Ti-fluorides are characterized by high vapor pressure. The appearance of such compounds ensures that alkaline earth metal fluorides are not wetted by Ti-containing melts at high temperatures exceeding 1400 K. This allows the use of fluorides crucibles as refractories for high-temperature melting, long-term homogenization and casting of alloys with a high content of Ti, Zr [1–4].
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Vitalyi Krasovskyy |
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H3-VT1032 |
Characteristics of hafnium after thermochemical treatment: influence of the surface layer state Vasyl Trush, Iryna Pohrelyuk, Alexander Luk’yanenko, Viktor Fedirko, Taras Kravchyshyn, Serhii Lavrys Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine Hafnium is used for production control rods and protective screens in nuclear reactors after its hot plastic deformation and final thermochemical treatment. This research presents the experimental results of the influence of the surface layer state on the oxygen diffusion saturation of hafnium during thermochemical treatment in an oxygen-containing gas medium. Two cases of the surface layer state were considered: in the initial (delivery) state and after grinding, where 50 µm of the surface layer was removed.
In this research, the differences in the distribution of hardness in the near-surface layer and fatigue life of the hafnium after thermochemical treatment in an oxygen-containing gas medium with the removed defective near-surface layer (after grinding) and not removed were shown.
It was found that for hafnium without removal of the surface layer after hot plastic deformation as a result of thermochemical treatment in an oxygen-containing gaseous medium (850°C for 2 h) in the near-surface layer, the hardness increases from the surface to a depth of 5...7 µm, and then decreases to the matrix stiffness values. Therefore, after the hot plastic deformation of hafnium, a defective «technological» layer of hafnium should be removed from the surface due to its chemical and structural heterogeneity, which can lead to premature failure of the product.
It was shown that thermochemical treatment in an oxygen-containing medium increased fatigue life compared to thermochemical treatment in a vacuum for hafnium without removal and with a removed surface layer. However, the thermochemical treatment in the oxygen-containing medium after grinding of hafnium specimens significantly increased the number of cycles to failure. The fatigue life of samples after thermochemical treatment of an oxygen-containing gas mixture with a removed surface layer is six times greater than the samples without removing the defective layers.
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Iryna Pohrelyuk |
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H3-YN1656 |
Nanocrystallization behaviour of amorphous Co67Fe4Cr7Si8B14 alloy Yulia Nykyruy, Stepan Mudry, Yuriy Kulyk Metal Physics Department, Ivan Franko National University of Lviv, Ukraine Amorphous metal alloys (AMA), also cold as glassy metals or metal glasses, are materials with disordered structure. For a long time they are in focus of researchers due to their unique mechanic, magnetic, electric and other properties. The properties of amorphous materials are related to a disordered structure and sensitive to structure transformation [1, 2]. Amorphous state is metastable one and under external influence, the evolution of the structure occurs, leading to drastic properties changes [3]. Therefore, investigation of structure evolution in these materials is an important research subject.
Our present research is focused on the crystallization behaviour of amorphous Co67Fe4Cr7Si8B14 alloy. This Co-based alloy was obtained by the melt-quenching method in the form of the ribbon 25 µm thick and 1 cm width. Structure transformations were studied by differential thermal analysis (DTA) using synchronous thermal analyzer Linseis STA PT 1600; back-scattered X-ray diffraction method (XRD) with X-ray structure analysis; field-emission scanning electron microscopy (FESEM), and vibrating magnetometer. The temperatures of the onset of the nanocrystallization, phase compositions, grain size and further structure transformations were defined.
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Yulia Nykyruy |
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H3-OS2211 |
Fractal analysis of the structure with non-metallic inclusions characteristics impact on the weld metal mechanical properties Viktor Holovko1, Olha Shtofel1,2, Iryna Krasikova3, Igor Krasikov3 1E. O. Paton Electric Welding Institute NASU, Ukraine The problem of improvement of welds metal structures and mechanical properties remain highly relevant due to the constant increase of high-strength low-alloy steels use in welded constructions. As is well known, the welds metalmechanical properties are determined by their microstructural components, including non-metallic inclusions. Existing analyzing methods of the influence of non-metallic inclusions do not provide sufficient information to describe such important parameters as the inclusions distribution by size and the nature of the inclusion distribution in the metallic matrix. The existing knowledge is based on the non-metallic inclusions peculiarities impact on the steel welds metal mechanical properties and requires constant expansion and deepening, which is the focus of this work.
To form different compositions and sizes of inclusions in the welds metal, high-melting point admixtures were added to the welding pool. The additives chosen were based on titanium compounds, including titanium oxide, titanium carbide, titanium nitride, as well as zirconium and magnesiumoxides.
The research was carried out for investigation thewelds metal structure fractal parameters influence on metal mechanical properties using computerized programs for welds metal structure fractal parameterization. It has been shown that in presence of acting stresses the non-metallic inclusions fractal dimension and the branching boundaries length fractal dimension are an efficient quantitative characteristic of the material structure self-organization process for individual samples.
The fractal dimension depends on the initial structure of the material and modifying effect of inoculants. It can be used in the development of new combinations of materials + inoculants. The data obtained allowed us to conclude that it is possible to predict the mechanical properties of the weld metal using fractal parameters of the structure and non-metallic inclusions.
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Olha Shtofel |
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H3-YS1552 |
Low-temperature physical and mechanical properties of doped non-equiatomic high entropy alloys of the Fe-Co-Ni-Cr system Yuri Semerenko1, Viktor Zoryansky2 1B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine High-entropy alloys (HEAs) were first manufactured in 2004 [1]. Initially, it was believed that such materials should consist of at least 5 elements, the concentration of which is close to equiatomic. At the same time, the structure of such HEAs will consist of simple single-phase solid substitution solutions with fcc or bcc lattices. It was also established that the strength of such equiatomic HEAs, by analogy with traditional alloys, can be further improved by reducing the size of grains in their structure to the nanoscale. However, the increase in strength of equiatomic HEAs with a decrease in grain size was accompanied by a harmful decrease in their plasticity and impact strength.
Efforts to overcome this obstacle have led to the appearance in the last few years of non-equilibrium multiphase non-equiatomic HEAs. In contrast to balanced single-phase HEAs, these materials were created on the basis of multicomponent solid substitution solutions with concentration of components different from the equiatomic. Thanks to activate alternative mechanisms of plasticity during preliminary deformation, it is possible to increase the plasticity of these HEAs while maintaining high strength. Such alternative mechanisms of plasticity are "plasticity induced by twinning" - TWIP and/or "plasticity induced by phase transformations" - TRIP.
It is hoped that further enhancement of the plasticity of such alloys is possible by adjusting the contribution of competing TWIP and TRIP mechanisms through doping [2, 3].
In this work, for the first time, the elastic and dissipative properties of doped non-equiatomic high entropy alloys of the Fe-Co-Ni-Cr system were measured and analyzed by the method of resonant mechanical spectroscopy. In a wide temperature range of 4.2–425 K, a correlation was established between the features of the temperature dependences of the dynamic Young's modulus and internal friction with changes in the phase and structural state.
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Yuri Semerenko |
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H3-YN1003 |
Features of the structural formation of tungsten single crystals in the shape of hollow rotational bodies Yuriy Nikitenko, Viktor Shapovalov, Volodymyr Yakusha, Oleksandr Gnizdylo, Olena Berdnikova Е.О. Paton Electric Welding Institute of the NAS of Ukraine Today, there is a need for single crystals of refractory compounds for the production of powerful solid-state lasers and ultrasensitive scintillators, as well as for the production of ultraviolet LEDs, which requires the production of highly active semiconductors grown using crucibles. There are certain requirements for these crucibles, such as minimal contamination of the melt, high operating temperatures (>1800°C), and a minimal CLTE, among others. Taking into account this set of properties, tungsten single crystals most fully meet these requirements.
Solving the issue of increasing the stability of tungsten crucibles is related to creating a defect-free, dense, and uniform structure.
According to the unique technology of growing single crystals of tungsten developed at the E.O. Paton EWI, an ingot in the form of a hollow body of rotation was made (Ø 85 mm, wall height 68 mm, and wall thickness 20-22 mm). This technology of growing is based on the layer-by-layer formation of the cylinder wall on a single crystal seed crystal.
The study of microhardness showed an average value of 4150 MPa for the vertical plane and 3840 MPa for the horizontal plane. A pronounced difference in microhardness in different planes indicates the anisotropy of properties inherent in a single-crystal structure. Conducting metallographic studies showed the homogeneity of the structure, the absence of defects between the deposited layers, and no grain boundaries were detected. The structure had clear subboundaries without dislocation density gradients. The distribution of dislocations in the volume of the single crystal was uniform, with a density of (4–6) 10*7 cm*-2. Subboundaries also had inhomogeneities in the form of dislocation plexuses when the density of dislocations increased. The calculation of misorientation angles based on diffraction patterns from substructure elements showed that was less than 2°, which did not exceed the permissible norm of 3°.
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Yuriy Nikitenko |
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H3-OS1449 |
Investigation of crystallization processes of Co68Fe4Cr4Si13B11 amorphous alloy by in-situ high temperature XRD method. Oleksanr Smolyakov1, Michal Strach2, Tetiana Dmitrenko2 1Zaporizhzhia national university, Ukraine There are a number of works [1-3] on the Co68Fe4Cr4Si13B11 amorphous metal alloys (AMA) crystallization study. The results presented in these works are contradictory in nature with respect to the phases that form during heating or annealing of this alloy. For example, it was indicated in [2] that crystallization under isothermal annealing conditions leads to the formation of solid solutions based on cobalt and Co3B boride. In [3], Co3B boride was not detected, but the formation of additional Co21Cr2B6, Co2B and Co2Si phases was indicated. Therefore, the aim of this work was a detailed study of the crystallization processes of AMA Co68Fe4Cr4Si13B11 during continuous heating at a rate of 6 K/min and after isothermal annealings. A study was carried XRD in-sity on a D8 Advance (Cu-K) diffractometer in the angle range from 40° to 50° in the temperature range from 303 to 1043 К.
It has been established that, upon continuous heating, the crystallization of the alloy began at a temperature of 773 K with the formation of hcp and fcc cobalt. Subsequently, at a temperature of 803 K, the samples completely crystallized with the appearance of additional diffraction peaks. At a temperature of about 923 K, these peaks disappeared with the appearance of new diffraction peaks. At a temperature of 1043 K, another similar phase transformation took place. To determine the phase composition of the samples in different heating temperature ranges, precision XRD studies of the samples after annealing at 823, 973, and 1073 K were carried out. An analysis of the results showed that, above a temperature of 1043 K, the alloy included phases based on hcp and fcc cobalt and Co2B. In the temperature range from 923 to 1043 K, the Co21Cr2B6 and Co2Si phases were additionally fixed. In the temperature range of 803–923 K, the alloy composition included phases based on hcp and fcc cobalt, Co3B, and one or two unknown phases.
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Oleksanr Smolyakov |
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H3-KS2213 |
Effect of the stress-strain state on the properties and structure formation of materials of the Fe-Al system under hot deformation Stepan Kyryliuk, Oleksandr Tolochyn, Oleksandra Tolochyna, Genadii Bagliuk Franctsevich Institute for Problems of Materials Science NAS Ukraine One of the directions for the creation of new materials at today's stage of scientific and technical progress is to obtain alloys and composites with predetermined properties. Fe3Al-based iron aluminides are considered as substitutes for stainless steels due to better resistance to corrosion, sulphidation, oxidation and a better strength-to-weight ratio. The study of the effect of the deformation scheme on the processes of structure formation and physical and mechanical properties is an urgent task for obtaining materials with specified properties.
To determine the evolution of the stress-strain state and densification in the process of hot deformation of materials of the Fe–Al system, a computer simulation of the hot forging process was carried out using the Deform 2D/3D software. The previously synthesized Iron aluminide Fe-28Al-5Ti (at.%) was subjected to deformation processing in a semi-closed die at temperatures of 800 and 1100°C. After hot deformation, the mechanical properties and microstructure of the samples were studied.
The simulation results show that residual porosity of the sample for a temperature of 800°C is uneven in volume (0–8.3%). At a temperature of 1100°C, the distribution of residual porosity is more uniform (0.6–0.7%).The experimental porosity of the sample deformed at temperatures of 800 and 1100°C is 3.8 and 0.9%, respectively. Analysis epures of the distribution of the total velocity vector and strain components showed at the initial stages, the axial strain component prevails, but after filling the matrix cavity, the radial strain component comes to the forefront. At the final stages of the process, the accumulation of deformations occurs due to the movement of material into the pore volumes during the compaction process. After hot deformation, the resulting structures are characterized by elongated grains and flat porosity. The bending strength of the samples obtained after deformation at 800 and 1100°C is 360 and 985 MPa, respectively.
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Stepan Kyryliuk |
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H3-SL0552 |
Feature of microstructural evolution and corrosion behavior Ti6Al4V alloy obtained from elemental powder blends Serhii Lavrys1, Iryna Pohrelyuk1, Dmytro Savvakin2, Khrystyna Shliakhetka3, Mariia-Olena Danyliak1 1Karpenko Physico-Mechanical Institute of the NAS of Ukraine Sintered Ti–6Al–4V alloys prepared from TiH2/60Al40V powder blends under various technological conditions were studied. The microstructural evolution was investigated by X-ray diffraction, scanning electron microscopy, optical microscopy, and energy dispersive X-Ray analysis. The corrosion resistance of sintered titanium alloy was evaluated by the static immersion test according to ASTM standard G31-72(2004) in 40 wt.% H2SO4 solutions. Depending on powder metallurgy processing parameters (powder size, compaction pressure, sintering temperature), the Ti6Al4V alloy was obtained with various structural features (porosity, chemical, and structural heterogeneity). It was shown that those structural features of sintered Ti6Al4V alloy are a key microstructural factor that determines their corrosion resistance. For instance, an increase in porosity leads to enhanced corrosion resistance. Based on the current research, the optimal parameters of powder metallurgy manufacturing of Ti6Al4V alloy, ensure the achievement of characteristics sufficient for practical use in aggressive conditions of the chemical industry.
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Serhii Lavrys |
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H3-ST6593 |
Microstructure and densification mechanism of Al-15Fe alloy prepared by metallurgy route Serhii Teslia, Anatoliy Stepanchuk, Mariia Kruzhkova, Daria Chyzhska, Danylo Sudakov Igor Sikorsky Kyiv Polytechnic Institute, Ukraine Aluminum-based alloys, due to their relatively high specific strength, low density, and high corrosion resistance, are the main materials for the production of multifunctional parts. Dispersion-strengthened aluminum alloys have a limited range of use due to the loss of properties at elevated temperatures.It is possible to increase high-temperature properties when using alloying elements with low solubility in aluminum, like iron. In this work, the conditions for obtaining Al-15Fe powder alloys by methods of pressing and sintering at different holding time were studied. The initial powders were obtained by centrifugal atomization, based on the prediction that due to the high cooling rate in this case (more than 10-5 K/s), the intermetallic phase will be in a dispersed state. The microstructural and XRD showed that their structure consists of a matrix phase with α-Al and inclusions of the metastable phase Al6Fe and the stable phase Al13Fe4. The paper studied the effect of powder particle size (100, 200, 282, 357 μm) and pressing pressure (300-800 MPa) on the process of their compaction using the static pressing method. The relative density of pressings increases monotonically with increasing pressing pressure from 300 to 800 MPa, from 75% to 96%, which is typical for the compaction of plastic materials. The size of the particles practically does not affect the degree of compaction.The process of sintering of the obtained samples at a temperature of 500 °C and a holding time of 30 min was studied. For all cases, there is a negative shrinkage, which decreases with increasing pressing pressure. The latter can be caused by the action of two competing processes - the pressure of crystallization and the action of sintering mechanisms, which contribute to shrinkage. During heating, a crystallographic transformation of metastable to stable Al13Fe4 phase occurs, which is accompanied by an increase in specific volume, which is the cause of negative shrinkage.
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Serhii Teslia |
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H3-AS1458 |
Phase equilibria of the Hf–Ni–Ti system at solidus temperatures Anastasiia Storchak, Maryna Bulanova, Tichonova Iryna, Samelyuk Anatoliy Frantsevich Institute for Problems of Materials Science NAS of Ukraine Hf-Ni-Ti alloys are of interest as amorphous materials. To control their properties, information on phase equilibria in the region of crystallization is necessary. The Hf-HfNi-TiNi-Ti subsystem was studied in detail in [1, 2] . Additionally, isothermal sections at 800 °С and 900 °С were plotted in [3]. The section HfNi-TiNi turned out to be quasibinary. No information is available concerning phase transformations in the crystallization interval in the subsystem HfNi-Ni-TiNi. The aim of the present study is to plot the solidus projection of this subsystem.
The alloys were melted in an arc furnace in Ar from iodide Hf and Ti and electrolytic Ni. The alloys were annealed for 30 h at subsolidus temperatures (by 20–40 °С lower than incipient melting temperatures of the as-cast alloys determined by DTA). Annealed and as-cast alloys were studied by differential thermal analysis (DTA), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD).
The projection of the solidus surface of the subsystem of interest is characterized by presence of 10 three-phase and 20 corresponding two-phase regions.
The main feature of the solidus projection is the presence of a new ternary compound (τ) of approximate composition 15Hf-65Ni 20Ti at. %. It melts congruently and has noticeable homogeneity region: from 64-66 at. % Ni and 17-22 at. % Ti. It is in equilibria with the following phases: (Hf,Ti)Ni, TiNi3, and βHfNi3.
The homogeneity regions of all the binary compounds at solidus temperatures widely extend to the ternary. Ti solubility in HfNi3, Hf7Ni10, Hf2Ni7, Hf3Ni7, Hf9Ni11, Hfi5Ni were established as 25.5; 14; 4.5; 4; 2 and 1 (at. %), respectively. TiNi3 has a large solubility region: from 64-66 at. % Ni and 17-22 at. % Ti. The continuous solid solutions (Hf,Ti)Ni dissolves up to ~10 at. % Ni. On the HfNi side the solubility decreases exponentially.
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Anastasiia Storchak |
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H3-AS1510 |
Projection of the liquidus surfase in the Hf–Ni–Ti system in the HfNi–Ni–NiTi region Anastasiia Storchak, Maryna Bulanova, Konstantin Meleshevich, Anatoliy Samelyuk Frantsevich Institute for Problems of Materials Science NAS of Ukraine The Hf-Ni Ti system is of great practical and scientific interest due to existence of wide region of amorphous state of alloys and shape memory alloys. In [1] the liquidus surface of the ternary system was studied in the range of nickel content 0-50 at. %. No experimental data on phase equilibria with participation of the liquid phase are available for the Ni-rich region. The thermodynamic modeling and calculation of the liquidus projection in the Hf-Ni Ti system was done in [2]. However, our results show the necessity of its experimental study.
The aim of the present work is experimental investigation of phase equilibria in the HfNi–Ni–NiTi region of the Hf–Ni–Ti system and construction of the preliminary liquidus surface projection.
The alloys for investigation were melted in an arc furnace in Ar from iodide Ti and Hf and electrolytic Ni. As-cast alloys were studied by differential thermal analysis (DTA), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray diffraction phase analysis (XRD).
The liquidus projection is characterized by the presence of primary crystallization fields of (Hf, Ti)Ni, (Ni), and all phases based on Hf-Ni and Ti-Ni compounds (nickel content 50-100 at. %), which in binary systems form with the participation of the melt. The largest field is for continuous solid solutions (Hf, Ti)Ni up to 64,5 at. % Ni.
The new congruent ternary compound (τ) of approximate composition 15Hf-65Ni 20Ti at. %, was found in the system. It has the wide primary crystallisation field within 62,5-68,5 at. % Ni and 15-27 at. % Ti.
There are 10 invariant four-phase equilibria with participation of the liquid phase.
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Anastasiia Storchak |
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H3-NR1653 |
Estimation of the Lattice Parameter and Distortion of Atoms Based on the Results of Ab initio Study of Structural Fragments of TiVZrNbMo, TiVZrNbTa, and TiVZrNbHf Multicomponent Equiatomic Alloys Nataliia Rozhenko, Liubov Ovsiannikova, Valery Kartuzov Frantsevich Institute of Materials Science Problems, National Academy of Sciences of Ukraine An approach is proposed for determining the lattice parameters and the degree of atomic distortion in multicomponent bcc alloys based on the results of an ab initio study of isolated atomic clusters – fragments of their structure. Isolated clusters - fragments of the bcc structure consisting of 15 and 65 atoms - were built. Three 15-atomic Ti3V3Zr3Nb3Mo3 equiatomic clusters have different disordered mutual arrangement of atoms. In the 65-atom Ti13V12Zr14Nb14Mo12, Ti13V12Zr14Nb14Ta12, and Ti13V12Zr14Nb14Hf12 clusters, the elements are arranged according to coordination spheres. The constructed clusters were studied in the framework of DFT methods using the Gaussian complex with the B3LYP hybrid functional and the STO-3G basis set and GAMESS with the PBE0 functional and the MINI basis set. The lattice parameter, determined from the optimized cluster geometry, was extended to the solid structure using a correction factor. The value of the lattice parameter of the equiatomic TiVZrNbMo alloy established from 15-atom clusters is 0.3231±0.0002 (nm) and coincides with the experimental value for the corresponding coating of 0.3230 nm [1]. The lattice parameters of the TiVZrNbMo, TiVZrNbTa, and TiVZrNbHf equiatomic coatings, calculated from 65-atom clusters, are 0.3222, 0.3280, and 0.3327 (nm), respectively, in agreement with the experimental values (0.3230, 0.3264, 0.3336 (nm), [1]). The root-mean-square deviation of the lengths of the radius vectors of the positions of atoms in a cluster from the radius of the corresponding coordination sphere of an ideal lattice was taken as a quantitative measure of distortions in the lattice. The calculated distortions are 0.011, 0.015, and 0.020 (nm) for the TiVZrNbMo, TiVZrNbTa, and TiVZrNbHf equiatomic coatings, respectively. The approach can be recommended for predicting the lattice parameter and distortion of new prognosticated multicomponent alloys.
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Nataliia Rozhenko |
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H3-KS2339 |
Development Status and Disadvantages of Well-Known TDA Methods for the Chemical Composition and Properties of Cast Iron Kateryna Sirenko, Valeriy Mazur Physical and Technological Institute of Metals and Alloys of the National Academy of Sciences of Ukraine The quality of castings depends on the processes that occur during the liquid iron stage, with optimal temperature conditions and compliance to regulated standards for metal composition. Melting and holding the metal affect furnace wear, volatilization, and energy consumption, increasing production costs. Melting time can be reduced by enhancing prompt quality control and adjusting composition before pouring into molds. Existing rapid analysis methods are limited to chemical analysis, except for thermal methods like Thermal Derivative Analysis (TDA).
TDA identifies critical temperatures on the cooling curve of liquid cast iron, dependent on structural components. By calculating derivatives, TDA provides reliable results for assessing the composition and structure of cast iron. However, implementing this method faces difficulties, necessitating scientific and technological development and improvement.
In TDA, the quality of liquid cast iron is evaluated by comparing its thermal cooling curve (TCC) with a reference cooling curve (RCC) from a database. RCC reflects the influence of microstructural components on the cooling curve, determined by latent heat release during solidification. Predicting the casting structure allows determination of quality indicators and chemical composition. The method's improvement lies in comparing TCC and RCC using a patented recognition criterion called Z (zet). A smaller criterion value indicates similar curve shapes, with a minimum or zero criterion implying the most similar pair and equivalent cast iron properties.
To implement the TDA method effectively, stability of sample volume and temperature, uniform heat dissipation, environmentally friendly sample collectors, and adaptable curve processing methods are crucial. Therefore, considering melted cast iron as an object of rapid thermal control, improving rapid chemical composition control, and exploring new efficient means for multi-elemental composition control are necessary.
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Kateryna Sirenko |
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H3-DC1711 |
The effect of ZrO₂ concentration on the optical properties of Y₂O₃ transparent ceramics Dariia Chernomorets1,2, Jan Hostaša2, Laura Esposito2 1Institute for Single Crystals of NAS of Ukraine Good optical and mechanical properties and thermochemical stability allow using optical Y₂O₃ ceramics for different applications. However, the process of obtaining this material is challenging due to the high melting point of Y₂O₃, and, therefore, sintering aids are used to reduce the sintering temperature and promote densification during the process [1]. For the presented work ZrO₂ was chosen, since it is one of the common sintering aids for producing Y₂O₃ ceramics [2]. The aim of the study is to establish the optimal concentration of ZrO₂ for obtaining transparent Y₂O₃ ceramics. The concentration of ZrO₂ varied in the range of 0–11 mol%. Transparent optical ceramics Y₂O₃:Zr⁴⁺ were obtained from a stoichiometric mixture of powders by uniaxial pressing followed by CIP (cold isostatic pressing) and vacuum sintering at 1735°C for 22 hours. The dependence of the optical characteristics of transparent Y₂O₃ ceramics on the concentration of ZrO₂ was investigated. It was established that 7 mol% is the optimal concentration that allows obtaining yttrium ceramics of the highest optical quality. This sample is characterized by full densification (100% of the theoretical value), homogeneous microstructure without defects, such as pores or secondary phases, and mean grain size of about 4.8 μm. The optical transmittance of this sample reached 80.2% at 1100 nm. When no sintering aid was used, significant grain growth was observed (about 14 μm) and the formation of almost opaque ceramics with a transmittance of 7.2% at 1100 nm. An increase in the concentration of ZrO₂ up to 7 mol% leads to an increase in optical transmittance. With the subsequent addition of a sintering aid, the optical properties of ceramics deteriorate slightly. At the same time, it is worth noting that the presence of secondary phases is not observed even at 11 mol% of ZrO₂. This indicates that for the studied composition range, a solid solution of ZrO₂ in Y₂O₃ is obtained without reaching the solubility limit.
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Dariia Chernomorets |
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H3-RY1355 |
Infrared transparent ceramics of complex architecture for extreme operating conditions Roman Yavetskiy, Olexandra Kryzhanovska, Nadiia Safronova, Dariia Chernomorets, Oxana Matvienko, Serhii Parkhomenko, Andrii Doroshenko, Ihor Vorona, Anton Balabanov, Arsenii Timoshenko Institute for Single Crystals of NAS of Ukraine Creating new transparent windows for modern infrared (IR) optics working in aggressive conditions is an urgent task of materials science. Such materials require high transparency, low emissivity, high thermomechanical stability. Existing materials meet the needs of optical quality, but most of them do not have sufficient thermomechanical properties. Composite nanoceramics are potentially able to combine high optical quality with extremely high heat resistance. Nanoceramics in Y2O3–MgO system are considered as promising optical materials for IR range due to excellent transparency, improved thermal shock resistance and mechanical strength. This work aims to study obtaining peculiarities of IR-transparent ceramics of complex architecture based on Y2O3–MgO system.
Y2O3 ceramics have been synthesized by reactive sintering method. The effects of starting materials, mesostructure of green bodies and processing conditions on the properties of Y2O3 ceramics were studied. Y2O3 ceramic samples of complex geometry were produced by slip casting. Influence of dispersant type and their concentration on Y2O3 suspensions stability was investigated. Rheological properties of Y2O3 slips were studied. Microstructure, optical properties and mechanical characteristics of hemispherical samples were determined.
50:50 vol.% Y2O3–MgO composite nanoceramics were produced using nitrate-glycine method and spark plasma sintering. Effect of heat treatment conditions on structural and morphological characteristics of Y2O3–MgO nanopowders was investigated. Influence of spark plasma sintering parameters of Y2O3–MgO nanopowders and ceramics properties were studied. Morphology, microhardness and IR-transmittance of Y2O3–MgO nanocomposites were determined. Hemispherical green body was obtained by slip casting. Effect of solid loading, dispersant type and its concentration on stability and rheological properties of aqueous Y2O3–MgO suspensions was investigated in details.
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Roman Yavetskiy |
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H3-OB1453 |
AlMgB14-related orthorhombic boron carbide phases from first principles: structure and mechanical properties Oleksiy Bystrenko1,2, Jingxian Zhang2,3, Dong Fangdong4, Xiaoguang Li2,3, Weiyu Tang2,3, Kaiqing Zhang2,3, Jianjun Liu2,3 1Frantsevich Institute for problems of materials science, National Academy of Sciences, Kiev, Ukraine We theoretically examine the effects produced by replacing interlayer boron-boron bonds in AlMgB14-related boron network by carbon-carbon bonds on its structure and mechanical properties. The equilibrium structure, elastic constants, Vickers hardness and shear strength are evaluated by means of first principle computer simulations on the basis of density functional theory by employing ultrasoft and PAW pseudopotentials with the use of GGA approximation. The obtained results support the conclusions of Ref. [1] concerning the importance of interlayer bonds in AlMgB14-related boron network for mechanical properties of compounds with related structure.
The results of simulations suggest a possibility of existence of a number of new orthorhombic boron carbide phases with enhanced mechanical properties with the theoretically predicted Young’s modulus of 550-620 GPa and intrinsic hardness of 43-50 GPa.
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Oleksiy Bystrenko |
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H3-TP3074 |
Structure, mechanical characteristics and high temperature stability of sintered under high and by hot pressing ZrB2- and HfB2– based materials without and with SiC and Si3N4 additions Tetiana Prikhna1, Anastasiya Lokatkina1, Pavlo Barvitskyi1, Myroslav Karpets2, Viktor Moshchil1, Semyon Ponomarov3, Johen Werner4, Bernd Büchner4, Richard Haber5, Zeynep Ayguzer Yasar5, Branko Matovich6, Robert Kluge4, Anatoly Bondar7, Olexander Borymskyi1, Leonid Devin1 1V. Bakul Institute for Superhard Materials of the National Academy of Sciences of Ukraine The study of the structure, mechanical characteristics and high temperature stability in vacuum and in air (DTA and TG measurements) of sintered under high quasiisostatic pressure (at
4.1 GPa) and by hot pressing (at 30 MPa) ZrB2 - and HfB2 – based materials without and with SiC and Si3N4 additions showed that the use of high pressures at comparatively low temperatures (1800oC) and short sintering time (8 min) makes it possible to obtain mentioned materials with improved mechanical properties as compared to all other known methods. The stability in vacuum of pure ZrB2 and HfB2 occurred to be essentially higher than that of the materials with SiC additions (the beginning of melting of the materials with additions observed at 2150-2160°C, while the materials without them did not melt up to 2970°C). The composite material prepared from HfB2 -30 wt.% SiC mixture demonstrated mechanical characteristics (density =6.21 g/cm 3, microhardness Hv(9.8 N) =38.1±1.4 GPa, H V (49 N) = 27.7±0.24 GPa, HV (98 N)=26.3±2.03 and fracture toughness K 1C (9.8 N) = 8.2±0.2, MH•m 0.5 , K 1C (49 H)=6.8±0.6 MH•m 0.5 , K 1C (98 N) = 6.4 ±0.11 MH•m 0.5 ) which are essentially higher than that of pure HfB2 sintered in the same conditions (=10.79 g/cm 3 , Hv(9.8 N)=21.3±0.84 GPa, HV (49 N)=19.3±1.34 GPa, HV (98 N)=19.2±0.5 and fracture toughness K 1C (49 N)=7.2±0.9 MH•m 0.5 , K 1C (98 N)=5.7 ±0.3 MN•m 0.5 , Young modulus E=984 GPa, Poisson ratio µ=0.146). The mechanical characteristics of high pressure sintered material from ZrB 2 +20 wt.% SiC (=5.04 g/cm 3 , Hv(9.8 N)=24.2±1.0 GPa, H V (49 N)= 17.6±0.7, H V (98 N)=16.73±1.1 GPa, K 1C (49 N)=7.21±1.55 MH•m 0.5 , K 1C (98 N)=6.2 ±1.24 MH•m 0.5 , E=386 GPa, µ=0.093) are higher than that sintered by hot pressing at 30 MPa, 1900 o C for 1 h from ZrB 2 +30 wt.% SiC (=5.25 g/cm 3 , Hv(9.8 N)=22.95±1.0 GPa, K 1C (9.8 H)=3.44±0.22 MH•m 0.5 ). The formation of solid solutions in the case of SiC additions to ZrB2 and HfB2 was confirmed by Auger quantitative analysis and Auger mapping.
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Anastasiya Lokatkina |
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H3-NU1224 |
Phase transformations during heat treatment of germanium-doped hydroxyapatite and their influence on physico-chemical and biological properties Nataliia Ulianchych1, Sergey Firstov1, Volodymyr Kolomiiets’1, Oksana Koriak1, Larysa Strilets1, Mykhailo Rublenko2, Tetiana Todosiuk2 1Frantsevich Institute for Problems of Materials Sciences of National Academy of Sciences of Ukraine The application of calcium phosphate ceramics (CPC) for bone repair is limited by its low bioactivity, which can be improved by the Ge-doping, which is a biologically active microelement. There is almost no published data on Ge doping effect on the properties of CPCs. In the current study, the Ge doping of hydroxyapatite (HAP) was carried out during the synthesis from solutions of calcium and phosphate salts via the introduction of 1.0 and 1.5wt% of Ge– metaphosphate colloidal solution. The material's structure, phase composition, solubility, and adsorption activity were determined.
The phase composition of HAP doped with 1.0 wt%Ge after annealing at T=800ºС is as follows: HAP–45%; α-tricalcium phosphate (TCP)–55%. The distinguishing feature of this process is the formation of the α-TCP phase, which is stable at T~1125ºС and has a higher solubility instead of β-TCP, which is stable at 800ºС. Annealing at 1200ºС leads to the formation of HAP–6%, β-TCP–55%, and α-TCP–39%, which are also atypical phase changes during annealing for TCP. The phase composition of HAP doped with 1.5 wt%Ge annealed at 800ºС was as follows: HAP–57%; α-TCP–10%; β-TCP–33%. That is too difficult to simultaneously obtain three biocompatible phases, with different solubility of each phase and due to the optimal structure formation, this leads to enhanced bioactivity. Changes in the phase composition of synthesized materials caused changes in solubility and adsorption activity, which were reported to be higher than in Si-doped HAP.
In vivo, studies of 1.0 wt% Ge-doped HAP on rabbit bones showed the significant osteoinductive properties of the material, manifested radiologically and macro-morphologically by dynamic phenomena of osteointegration and early remodeling of bone tissue. It was confirmed histomorphologically that the formation of ‘bone regenerate’ is significantly accelerating and have better quality if compared with Si-doped HAP.
The Ge-doped HAP shows the enhanced bioactivity of CPC.
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Nataliia Ulianchych |
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H3-LK1250 |
Effect of Mn doping on structural and optical properties of (Zn,Mg)O ceramics Iryna Markevich1, Tetyana Stara1, Yuliia Polishchuk1, Semyon Ponomaryov1, Kostiantin Kozoriz1, Oleksandr Melnichuk2, Lyudmyla Melnichuk2, Nadiia Korsunska1, Lyudmyla Borkovska1, Larysa Khomenkova1,3 1V. Lashkaryov Institute of Semiconductor Physics at the National Academy of Sciences of Ukraine Manganese-related luminescence has been reported for Mn-doped ZnS and ZnSe. Contrary to ZnS and ZnSe, ZnO is more attractive as a non-toxic and environmentally friendly material. Due to the large exciton binding energy (60 meV), ZnO demonstrates bright, room-temperature UV emission. In addition, ZnO shows visible emission whose intensity and spectrum can be controlled by certain treatments and by doping with different impurities. However, Mn doping causes the dramatic quenching of intrinsic ZnO luminescence, and, in contrast to ZnS:Mn and ZnSe:Mn, this quenching is not accompanied by an appearance of Mn-related emission.
To clarify this issue, in the present work the ZnO was doped with Mn and Mg simultaneously. The use of magnesium permitted the formation of Zn1-xMgxO solid solution with a bandgap larger than that of ZnO. The Zn1-xMgxO samples with [Mn]=0.1at% were prepared by sintering at 900-1200 C for 3 hours in the air and their structural, electric and optical properties were studied by XRD, EPR, diffuse reflectance, photocurrent and photoluminescence methods.
It was observed that (Zn,Mg)O:Mn alloys are dominated with wurtzite phase for x<0.25. The largest band gap was found to be Eg = 3.65 eV. Optical absorption and photocurrent spectra exhibit broad unstructured bands originating from the photoionization of MnZn2+ ions. They demonstrate the same onset at 2.16 eV which is blue-shifted with respect to ZnO:Mn one (set at 2.0 eV). Thus, MnZn energy level in wurtzite alloy is settled at 2.16eV below conduction band bottom. However, the excited states of MnZn2+ ions, including the lowest one, are still located in conduction band, which implies the absence of the MnZn2+ luminescence. It was concluded that a further increase of the bandgap of Zn1-xMgxO wurtzite alloys is desirable. It is assumed that achieving a bandgap larger than 4 eV will permit to shift down the lowest excited state of MnZn2+ ions inside the bandgap and achieve the Mn-related light emission.
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Larysa Khomenkova |
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H3-OV1525 |
Machine Learning assisted structure optimization and mechanical properties assessment of Si-doped boron carbide Oleksandr Vasiliev, Vladyslav Bilyi, Valerii Bekenev, Valerii Kartuzov Frantsevich Institute for Problems of Materials Science NAS of Ukraine In the recent decade, the possibility of improving boron carbide's performance at high-velocity impact with silicon doping received significant attention. While some optimistic results were achieved in experiment, several DFT studies found no improvement of the target properties, leaving the mechanism of improvement unclear. In this work, we used Machine Learning approaches to take a closer look at possible ground states in the system in an attempt to elucidate the mechanism. We trained high-precision Machine Learning interatomic potentials model (MLP) for the B₁₃₋ₓC₂Siₓ (x≤1) system with the NequIP package [1] using in-house DFT training data derived from the refined structure [2]. The model was further used in a simulated annealing algorithm to find optimal positions of Si atoms in angular chains in 2×2×2 and 4×4×4 supercells. The optimization results indicate that the dopant atoms tend to arrange themselves in parallel planes of the \{$1\bar{1}00$\} family with the closest atoms displaced in opposite directions. Such configuration has the lowest energy in the Si containing system. The MLP was also used in a hybrid DFT-ML procedure to assess the elastic moduli of the ground state. The resulting bulk modulus is virtually the same as that for boron carbide and shear and Young's moduli are up to 7 and 6% higher respectively. Thus, incorporation of Si and subsequent structural adjustments potentially have positive influence on the mechanical properties, which is rather small to be responsible for significant improvement. Further DFT studies of B₁₂C-C-C and B₁₂C^Si^C behavior under extreme uniaxial strain in direction parallel to the chain suggest that the middle carbon in the undoped boron carbide can temporarily change its chemical identity, possibly causing a "chemical lock" of the deformation. No changes are expected for the silicon containing chains, and the structure can freely recuperate to the initial when the strain is released.
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Oleksandr Vasiliev |
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Poster session Important.session is online-only and include 5 min presentation in the common conference room and 1 hour of discussion in individual rooms (Zoom) |
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H3-AG2356 |
Influence of Lead Oxide Addition on the Electrical Characteristics of Tin Oxide Based Ceramic Varistors Alexei Gaponov Oles Honchar Dnipro National University, Ukraine The ceramic varistors are often used to protect electronic devices from overvoltage. One of this is SnO2 - Co3O4 - Nb2O5 - Cr2O3 ceramics which has high nonlinear current-voltage characteristics. This ceramics must have low breakdown electric field and low leakage current (low-field electrical conductivity) for varistor application. For this purpose we decided to add the oxide PbO to the SnO2-based ceramics. In this investigation the electrical properties of (99.4-x) SnO2 - x PbO - 0.5 Co3O4 - 0.05 Nb2O5 - 0.05 Cr2O3 ceramics (x = 0, 0.1, 0.5, 0.7, 2, 4 and 8 mol.%) are studied. The samples were obtained by traditional technology. The axial pressure was 45 MPa, the sintered temperatures were 1050, 1150, 1250 and 1350C (1 hour) and the Ag-electrodes prepared at 800C (10 min) were used. The studied ceramics consists of SnO2 grains and Pb-rich secondary phases at the grain boundaries. They influence on the shrinkage of samples which is increasing from 1.6% for the sample without PbO addition sintered at 1050C to 11.3% for the sample with 8 mol.% PbO addition sintered at 1350C. The Pb-rich secondary phases are also responsible for the low breakdown electric field of varistors. We received the minimal value 1.3 kV/cm for the sample with 2 mol.% PbO addition sintered at 1350C (cf. 3.1 kV/cm for samples without PbO addition). The investigated varistors have a high value of nonlinearity coefficient 24 - 25 for the samples with 0.5 and 0.7 mol.% PbO additions sintered at 1150 and 1250C. Such samples have low values of low-field electrical conductivity 7.4 - 27 pS/cm (cf. 120 - 310 pS/cm for samples without PbO addititon). These parameters are explained by the high Shottky type potential barriers (0.9 - 1.1 eV) on the SnO2 grain boundaries. Thus, the low leakage current and the low breakdown voltage can be received with adding PbO oxide to SnO2-based varistors. Optimal concentrations of PbO addition are 0.5 - 0.7 mol.% and optimal sintered temperatures are 1150 - 1250C.
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Alexei Gaponov |
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H3-SK1252 |
Synthesis of alkaline nitride glasses and their physical and chemical properties Eugen Pashchenko, Denys Savchenko, Svitlana Kukharenko, Sergiy Skorokhod, Roman Kurganov Bakul Institute for Superhard Materials of the National Academy of Sciences of Ukraine We introduced nitrogen into the molecular glasses mesh in order to obtain microporous binders with high adhesion to the synthetic diamond surface and optimal physical and mechanical properties for creating abrasive composites with advantage in the processes of precision grinding of complex profiled products. This is the combination of a significant volumetric content of micron-diameter spherical cavities, as well as high physical and mechanical properties like nonporous high-melting glasses.
Oxynitride glasses in the Si–Zr–Na–Li–K–B–O–N system were produced by incorporating Si3N4 into the glass structure. This system is an oxynitride analogue of the widely known alkali-resistant (AR) glass. Batches of glasses containing from 1 to 5 at. % of nitrogen were produced.
Oxynitride glass analogues with a high zirconium content can be produced with the addition of Si3N4 and the use of a remelting stage. A significant increase in properties is observed with the introduction a few atomic percentages of nitrogen. Oxynitride glasses have demonstrated both increased chemical resistance and reduced deposition at the material-lubricant-coolant interface in strong alkaline environments under harsh aging conditions. The combination of improved initial strength and increased chemical resistance opens up significant potential for the use them in tooling composites.
The developed technology of nitride glass synthesis and the creation of highly effective diamond-containing composites based on them opens up the possibility of producing elite grinding wheels for especially responsible conditions of application combining extremely high dimensional stability, close to the stability of wheels on metal binders, with high cutting capacity of polymer and ceramic binders.
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Denys Savchenko |
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H3-VG1222 |
Study of silicon carbide and silicon nitride ceramics by the method of acoustic emission Victor Goncharuk, Irina Goncharova, Vadim Tsyvilitsin, Mykola Iefimov Frantsevich Institute for Problems of Materials Science, NASU, Ukraine The method of acoustic emission (AE) has recently been increasingly used in science and technology, due to the fact that the processes of deformation and destruction serve as sources of AE, the signals of which can provide detailed information about these processes. AE in a material can be caused by such internal sources as sliding, twinning, phase transformations, cracking, and friction processes. In this work, reaction-sintered silicon carbide materials (SCM) with different ratios of fractions of the initial SiC were studied: M5 monofraction with an initial particle size of d<SiC> = 5 μm (SCM-1) and polyfractional composition 40%M100 + 40%M28 + 20%M10 (SCM-2). These materials are also known as self-bonded silicon carbide (SCC) and in addition to SiC they contain 10-12% free silicon. Also investigated: reaction-sintered silicon nitride ceramics (RSNC) with an initial particle size of d<Si3N4> = 3-5 μm and a hot-pressed composite Si3N4+5%Y2O3+2%Al2O3+(0-50%)TiN(HPNC+TiN) with an initial particle size of d<Si3N4> = 1 µm, d<TiN> = 3-6 µm. In this work, the AE method was used to study the main mechanical characteristic of ceramic materials - the 3-point bending strength σr. Two methods have been proposed for estimating the bending strength: 1 - by the magnitude of the total AE amplitude; 2 - by the transition stress from discrete to continuous AE. Some advantage of the second method is a relatively low stress during preloading of a controlled sample σ = 0.8σr, while in the first method σ = (0.5-0.7)σr. However, when using both methods, preloading did not negatively affect the bending strength of the material. The average estimation error according to the proposed methods does not exceed 3%, which is about 5-6 times more precisely, than in the traditional assessment (≈20%) of the bending strength by the average sample value.
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Victor Goncharuk |
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H3-MZ1221 |
Mechanical and dielectric properties of ceramics based on Si3N4 produced by spark plasma sintering Maryna Zamula, Valerii Kolesnichenko, Nadiya Tyschenko, Oleksandr Shyrokov, Artur Stepanenko, Hanna Borodianska, Andriy Ragulya Institute for Problems of Materials Science National Academy of Sciences of Ukraine Due to its mechanical properties at room and high temperatures, the dense Si3N4 ceramic is a candidate for radio-transparent materials operating under extreme conditions. BN, which has a lower density and lower permittivity than Si3N4, can be a candidate for reducing permeability[1,2]. The work is devoted to the study of the influence of oxide additives on the α→β phase transformation in Si3N4 under spark plasma sintering (SPS) conditions and the study of mechanical and dielectric properties. SPS of Si3N4–Y2O3, Si3N4–Y2O3–SiO2, and Si3N4–Y2O3–BN was carried out in a heating rate of 50 K/min and a pressure of 35 MPa. It was established that the complex addition of Y2O3-SiO2 contributes to the formation of a significant amount of liquid phase and ensures compaction by rearranging Si3N4 nanoparticles under pressure. The slower consolidation of ceramics, with the addition of only Y2O3, is explained by the local interaction of Y2O3 and SiO2, which is manifested on the surface of Si3N4 particles. It was found that during SPS, for complete densification of Si3N4, 5 min of exposure at 1800°C is required for Si3N4–Y2O3–SiO2 and more than 30 min for Si3N4–Y2O3. Si3N4–Y2O3 and Si3N4–Y2O3–SiO2 composites showed flexural strengths of ~860 and 910MPa at room temperature and a gradual decrease in flexural strength to ~200MPa with temperature up to 1400°C. The resulting strength at room and elevated temperatures, HV of ~15GPa and 16GPa, and fracture toughness of ~7.5 MPa·m1/2 meet the current level of requirements for this ceramic. The Si3N4–Y2O3–BN composite shows ~30% lower mechanical properties compared to Si3N4–Y2O3, which can be explained by the presence of graphite-like BN, which has significantly lower hardness. The results of radio frequency measurements of composites based on Si3N4 showed that the addition of 10% BN reduces the dielectric constant of the Si3N4–Y2O3–BN composite by ~0.5. In addition, a residual porosity of ~10% further reduces the dielectric constant by ~1.
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Maryna Zamula |
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H3-VN2117 |
3D printing of the ceramic materials based on Mo₀.₉Cr₀.₁Si₂ by Robocasting technique Vladyslav Naumenko, Ostap Zgalat-Lozynskyy, Dmytro Zyatkevych Institute for Problems of Material Science, National Academy of Sciences of Ukraine To obtain products of complex shape by from high-melting point materials using traditional technology are quite difficulty. This problem can be solved via utilization of additive technologies (AM). One of them could be used for forming of workpieces of complex shape is Robocasting. Research shows that this method is promising for the formation of bioceramics, but for refractory compounds, such works are few [1]. The purpose of this work is to study the peculiarities of the formation of the structure and shape of a 3D printed product by Robocasting depending on various printing and processing parameters. Mo0.9Cr0.1Si2 solid solution powder was used as the starting material. To prepare the paste, the powder was mixed with a solution of synthetic rubber in gasoline. Robocasting studies were performed on 3D printers ZMorph 2 with a ceramic module and an Ender 5 with a Stoneflower clay module. The optimal composition of the prepared paste was 62.5 wt.% powder and 37.5 wt.% binder. The influence of 3D printing parameters on the quality of obtained samples was investigated. The dependence of the sample surface roughness from the size of the powder in paste was established. Submicron powder allows one to get a smoother, non-porous surface of the printed sample. The printed samples were heat treated for 2h at 400 ⁰С to remove the plasticizer and sintered at 1400 ⁰С for 1h. After sintering, the density of the samples was 4.38 g/cm³, which corresponds to a relative density of 70%. The relatively high porosity of the samples could be related with delamination of layers during thermal treatment and sintering of the samples. This indicates the need for a comprehensive approach to obtaining products using the Robocasting from pastes formation to development of regimes for heat treatment and consolidation.
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Vladyslav Naumenko |
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H3-ID2129 |
Scale particles from rocks - fillers for polymer composite materials Iryna Diduk, Olga Jashchenko, Kateryna Krasnikova Institute for Problems of Materials Science of NAS of Ukraine An alternative to fibrous fillers in the production of engineering composite materials are reinforcing dispersed fillers. In this work, an attempt was made to use scaly materials based on raw materials from rocks (basalt). Fillers with scaly-shaped particles are a special class of fillers for various types of compositions. Features of the structure allow them to be easily crushed or split to minimum sizes. The structure of the scale and obtaining a relief pattern of the image was carried out by the method of microscopy. When performing the work, methods of physical and chemical analysis of inorganic substances, methods of control of composite materials in accordance with the requirements of regulatory documentation were used. The resulting scale contains particles of various shapes (spherical, prismatic, lamellar or scaly, fibrous or needle-like) with a thickness of 1.0 to 4.5 μm and a size of 0.1 to 5.0 mm. In its original state, the basalt flake has a glassy structure, with a relatively smooth surface, but with some defects in the form of unmelted inclusions and submicrocracks. During the heat treatment of basalt scales, the ratio of iron oxide content changes significantly, the transition of FeO to Fe2O3 occurs at a temperature of 450-900 oC and higher. Heat treatment affects the appearance of a crystalline phase, which causes an increase in the density of the material by (10-20)%. A clear increase in density begins after a temperature of 450°С, and at a temperature ≥ (900 – 1000)°С it increases from 2.85 g/cm3 in the initial state to 3.04 - 3.08 g/cm3. Depending on the temperature and exposure time, the scale samples differ in their characteristics and color scheme.
The advantage of scales is the positive effect of the orientation of its particles when processing filled compositions. It can be assumed that the correct combination of scales and rock fibers will provide a better combination of strength, stiffness and impact strength of the filled compositions.
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Iryna Diduk |
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H3-IH9494 |
Increased wear resistance of end seal rings due to the use of improved ceramic material based on silicon carbide Ihor Hnylytsia Ivano-Frankivsk National Technical University of Oil and Gas, Ukraine In recent years, much attention has been paid to the development of new and improvement of existing materials in the C / SiC, SiC / SiC system. One of the promising areas for improving the properties of silicon carbide ceramics is the use of nanosized additives. The initial charge of silicon carbide powder, graphite powder in the amount of 12% and nano-sized additives of silicon and chromium carbides with a size of 30 nm in the amount of 1-8% was mixed in two conical mixers. A plasticizer (12% solution of bakelite in ethyl alcohol) was added to the prepared charge, dried and pressed in a mold with a moving matrix at a pressure of 200 kg/cm2. When the optimal pressure was exceeded, cracks were observed due to the elastic aftereffect. Pressed blanks were dried in a drying cabinet at a temperature of 150-180 0C for 8 hours to polymerize bakelite. Sintering was carried out in a vacuum induction furnace for 60 minutes at a temperature of 2000-2100 0С. The criteria for assessing the effect of nano-sized additives depend on the initial structure of the material, the features of the structural components and their relative arrangement. It is difficult and not always possible to assess such an effect from images of the structure. For materials based on self-bonded silicon carbide, the amount and nature of the placement of the intergranular phase, which is formed from free silicon and everything dissolved in it, has a significant impact on the structure and properties. An increase in the amount of the intergranular phase disrupts the integrity of the framework of silicon carbide particles, reduces the number of contacts between them and leads to a decrease in the hardness and crack resistance of the material. Known results indicate that reducing the amount of intergranular phase and reducing the number of contacts (bridges) between separate areas of free silicon is possible due to the use of nanosized additives. The density of the samples without nanosized additives was obtained at the level of 3.04-3.06 g/cm3. When using nanosized additives, there is a complex nature of the dependence of density on the content of additives. For samples of all compositions, the minimum density at the level of 2.7-2.8 g/cm3 was obtained at a content of 3-4% nanopowders and an increase of almost 3.1 g/cm3 (for SiC additives) at a content of 6% nanosized additives. With increasing content of nanosized additives, the density of all obtained samples was less than 2.7 g/cm3. In result we can talk about the positive effect of nanosized additives of silicon carbide and chromium carbide in the amount about 5% on the formation of the structure and properties of silicon carbide based materials. Field tests of the manufactured rings showed that the characteristics of silicon carbide end seal rings with nano-sized additives are 10-15% higher than the material without additives.
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Ihor Hnylytsia |
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H3-GO1610 |
On the methodology of generalization of knowledge about the structure formation of ceramic materials to implement it in technology Galyna Oleynik, Andrii Kotko I.M. Frantsevych Institute for Problems of Material Sciences NAS of Ukraine One of the new approaches to the development of ceramic materials is the design of microstructure. Previously, we have proposed a concept of such a design on the basis of the assembly of material with pre-planned elements of microstructure that determine the formation of its required service properties. Generalization and systematization of relevant information along are urgent tasks for the implementation of the accumulated knowledge on the structure formation of materials in the technology of their production and the development of new materials. In this report, an approach is proposed to generalize the relevant information in order to use it in both the control of service properties of known materials and the development of new ones. As the basic structural component of any ceramic material is a grain, it is logical to classify ceramic materials by the characteristics of both the grain structure of materials and the elements of the grain substructure. Important characteristics of grains are size, crystal morphology, composition, character of spatial distribution, and the structural state of intergranular and interphase (in composites) boundaries. Elements of the grain substructure are dislocation subboundaries, stacking defects, growth twins, deformation twins, inversion twins, domains, interfacial boundaries with inclusions of other phases, and pores of different crystal morphology. Each ofthem can be classified according tothe structural mechanisms of their formation. The generalized knowledge about the structure formation of ceramic materials can be used for introducing it into the improvement of known technologies and the development of new ones based on the knowledge. On the example of SiC ceramics, an algorithm for microstructural design of a material for constuctive purposes is proposed. The main components for the microstructural design of this material are identified.
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Galyna Oleynik |
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H3-GO1659 |
Structure formation of ultradispersed detonation diamond Galyna Oleynik, Andrii Kotko, Yurii Solonin I.M. Frantsevych Institute for Problems of Material Sciences NAS of Ukraine Ultradispersed diamond (UDD) obtained by detonation synthesis is a unique powder material. This is due to such characteristics as the size of nanoparticles (3-10 nm) and the presence of particles of anomalous size (much larger than the above: from hundreds of nm to tens of µm). Despite the fact that UDD was synthesized in the world in the early 80s of the last century, the mechanism of its formation has not yet been established. The purpose of this work is to determine the nature of the basic characteristics of UDD: the mechanism of formation of UDD as a substance from the initial structural state and the mechanisms of formation of powder structure components. The research was carried out by TEM combined with microdiffraction. There were studied UDD, the diamonds of dynamic synthesis and static synthesis. It was established that flat particles of the above types of diamond are characterized by a rail substructure, which is formed as a result of the martensitic transformation of graphite in to a diamond of hexagonal and cubic modifications. That is the rail substructure is a diagnostic indicator of such a transformation. Thus, it can be reliablystated that the formation of UDD stems from graphite. It was determined that the rail substructure in all of the diamonds is qualitatively similar. Rails based on the lonsdaleite contain basal packing defects, while two-phase rails contain defects of the lonsdaleite phase and streaks of the cubic phase with twins. In the rails, a phase transformation occurs with the orientation ratio (111)a||(001)l, [110]a||[1120]l, which initiates mechanical stress leading to the destruction of the rails. At the stage of the phase transformation, particles of anomalous sizes are formed. This proces sis provided by two mechanisms: (i) homoepitaxial сoalescence of nanoparticles during contacts of rails and (ii) in groups of randomly distributed particles processes characteristic for the sintering of loose powders take place: the zonal formation of coarse particles.
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Galyna Oleynik |
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H3-AG2282 |
Influence of lead oxide addition on the electrical characteristics of tin oxide dased ceramic varistors Alexei Gaponov Oles Honchar Dnipro National University, Ukraine The ceramic varistors are often used to protect electronic devices from overvoltage. One of this is SnO2 - Co3O4 - Nb2O5 - Cr2O3 ceramics which has high nonlinear current-voltage characteristics. This ceramics must have low breakdown electric field and low leakage current (low-field electrical conductivity) for varistor application. For this purpose we decided to add the oxide PbO to the SnO2-based ceramics.
In this investigation the electrical properties of (99.4-x) SnO2 - x PbO - 0.5 Co3O4 - 0.05 Nb2O5 - 0.05 Cr2O3 ceramics (x = 0, 0.1, 0.5, 0.7, 2, 4 and 8 mol.%) are studied. The samples were obtained by traditional technology. The axial pressure was 45 MPa, the sintered temperatures were 1050, 1150, 1250 and 1350C (1 hour) and the Ag-electrodes prepared at 800C (10 min) were used.
The studied ceramics consists of SnO2 grains and Pb-rich secondary phases at the grain boundaries. They influence on the shrinkage of samples which is increasing from 1.6% for the sample without PbO addition sintered at 1050C to 11.3% for the sample with 8 mol.% PbO addition sintered at 1350C. The Pb-rich secondary phases are also responsible for the low breakdown electric field of varistors. We received the minimal value 1.3 kV/cm for the sample with 2 mol.% PbO addition sintered at 1350C (cf. 3.1 kV/cm for samples without PbO addition).
The investigated varistors have a high value of nonlinearity coefficient 24 - 25 for the samples with 0.5 and 0.7 mol.% PbO additions sintered at 1150 and 1250C. Such samples have low values of low-field electrical conductivity 7.4 - 27 pS/cm (cf. 120 - 310 pS/cm for samples without PbO addititon). These parameters are explained by the high Shottky type potential barriers (0.9 - 1.1 eV) on the SnO2 grain boundaries.
Thus, the low leakage current and the low breakdown voltage can be received with adding PbO oxide to SnO2-based varistors. Optimal concentrations of PbO addition are 0.5 - 0.7 mol.% and optimal sintered temperatures are 1150 - 1250C.
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Alexei Gaponov |
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H3-ID1515 |
Glass and fibers based on silicate-hafnium and silicate-boron-hafnium systems Iryna Diduk, Yurii Chuvashov, Olga Jashchenko, Nataliya Koshelenko Institute for Problems of Materials Science of NAS of Ukraine Availability and cheapness of rocks made it possible to use them to obtain fibers and products based on them. The use of natural raw materials makes it possible to produce environmentally friendly materials resistant to atmospheric influences and aggressive environments. At the present time, special interest is shown in the production of radiation-protective compositions for special applications. Investigation of glass formation and fiber formation in silicate-boron-hafnium systems, namely rocks (andesite-basalts) plus HfO2; andesite-basalts plus HfO2–В2О3 are carried out in this research. The influence of individual components of the initial components on the properties of melts, glasses and fibers was determined by selecting raw materials, studying the compositions and physicochemical properties of multicomponent systems. Melts and glasses were produced in laboratory high-temperature furnaces, and the processes of fiber formation were studied on a universal high-temperature single-filament laboratory stand. For andesite-basalt modified 0.5; 1.0; 1.5% (wt.) HfO2 melting temperature range is 1165-1400 oС, for 2.0; 5.0; 6.0% (wt.) HfO2 – 1165-1450 oС. Melts are characterized by a smooth, shiny surface with a visible metallic luster. The microstructure of glass with hafnium additives from 0.5 to 6% (wt.) differs from the microstructure of the original glass from andesite-basalt by the presence of more pronounced liquation zones. The melt with 6% (wt.) HfO2 has a high viscosity, which does not allow obtaining an amorphous state by the quenching method. To reduce the viscosity of the melt, 5% (wt.) B2O3 was additionally introduced. The melt modified with HfO2and B2O3, 6 and 5% (wt.), respectively, has close values of the temperature dependence of viscosity relative to the initial melt from andesite-basalt in the temperature range of 1250-1450 °C. Laboratory samples of continuous fibers from modified melts were produced. The temperature range of fiber formation was 70oС.
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Iryna Diduk |
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H3-ID1956 |
The influence of aluminum oxide on the physical and mechanical properties of silicate fibers Yurii Chuvashov, Olga Yashchenko, Iryna Diduk, Nataliya Koshelenko Institute for Problems of Materials Science of NAS of Ukraine Volcanic rocks, as a complex silicate system consisting of oxides of alkaline and alkaline earth metals, are characterized by a wide diversity of oxides in their composition, including aluminum oxides. The study of the effect of aluminum oxides was carried out on specially prepared samples from the raw materials of natural silicate systems of the main composition (rocks of the basalt type), melts, glass and fibers. Fibers from raw materials from different deposits, obtained under the same conditions of formation, almost do not differ in strength. However, glasses with a larger total amount of Al2O3, SiO2, Fe2O3, TiO2 oxides have a positive effect on fiber strength due to strong bonds in the Al – O, Si – O, Si – O – Fe system. At the same time, aluminum oxide has a pronounced effect on the strength indicators, which is due to both the high strength of the Al-O bond and the formation of the alumino-silica structural frame of the glass. It has been studied that in glasses and fibers with an increase in the content of aluminum oxide, an increase in the glass transition temperature and an increase in the temperature of the upper limit of crystallization are observed. With a high content of aluminum oxide, the crystallization of basalt glass and fibers with increasing temperature occurs with the formation of aluminous magnetite (magnetite containing more than 15% Al2O3); growth of augite crystals (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 and, subsequently, with the formation of Ca[Al2Si2O8] anorthite. At a low content of aluminum oxide, crystallization takes place with the formation of augite (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6. The temperature interval for the production of continuous fibers and their diameter was (1380-1450) oC and (9-15) microns, respectively; coarse fibers - (1300-1400) oC and (180-400) microns. The strength of the fibers is related to the scale factor, because the larger the diameter and length of the fibers, the lower their strength.
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Iryna Diduk |
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H3-DK2014 |
Preparation of Ti3SiC2 MAX phases using high-energy ball milling of the initial components in a planetary mill Maria Savyak, Dmytro Korablov, Alla Коpаn, Yuriy Solonin Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Layered ternary carbides (MAX phases) are large collection of oxygen-free ceramic materials exhibit a unique combination of properties characteristic of both metals and ceramics. MAX phases are hard materials which are metallically conductive and thermally conductive. Such materials have low density, Young’s modulus values on the order of 300 GPa, excellent corrosion resistance in aggressive liquid media, resistance to high temperature oxidation and has high melting point. Among the many MAX-phases synthesized to date, the greatest interest from the standpoint of the level of their properties represents such material based on titanium as Ti3SiC2.
Synthesis of MAX phases is carried out mainly by methods of hot isostatic pressing, spark plasma sintering and by the method of self-propagating high-temperature synthesis (SHS). These processes are quite complex, can be difficult and non-technological. In order to obtain MXenes it is desirable to synthesize MAX phases in the form of a dispersed powder to improve etching of A-element layers. Herein, the preparation of Ti3SiC2 MAX phases using high-energy milling of the initial components in a planetary mill has been studied with a view to improve the quality and purity of resultant MXene.
In the present investigation the milling of reactants was performed in argon atmosphere in a planetary mill AIR-015M. The phase composition of the samples was examined by XRD using a diffractometer "DRON 3" (Cu Kα radiation).
The effect of the content of the mixture components, its purity, the energy intensity of the mill (rotation speed, ball-to-powder ratio) and the milling time on the formation, in particular on the purity of Ti3SiC2 phase has been studied by numerous experiments. It is shown that in the 3Ti–Si–2C systems Ti3SiC2 MAX phase with a small amount of TiC, TiSi2, Ti5Si3 impurities can be formed as a result of the reaction of mechanically activated self-propagating synthesis.
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Dmytro Korablov |
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H3-SL1034 |
Phase diagram of the Fe7Se8–Bi2Se3 system Serhii Lakiza, Kingshuk Bandopadhyay, Krzysztof Markus, Yaroslav Korol Ensemble3 sp. z o.o. 01-919 Warsaw 133 Wólczyńska St., Poland The three-dimensional (3D) topological insulators (TIs) have been of increasing theoretical and experimental interest due to their topologically protected surface states. As the electron’s spin and momentum on the surface of a TI are essentially interlocked, it has become a source of new physics and advanced spintronic devices. To achieve that, there has been intense interest in TI-based heterostructures with different magnetic materials like ferromagnetic, antiferromagnetic, superconductor, etc. Iron-chalcogenides have recently attracted great interest due to the recent discovery of superconductivity in Fe1-xSe-based compounds. Among them, Fe7Se8 single crystals, due to their high iron concentration, are characterized by the high magnetic ordering temperatures (Néel temperature ~450 K). Fe7Se8 has a simple NiAs-type structure with filled layers of a chalcogenide, with hexagonal packing, alternate with metal layers with vacancies. The magnetic moments of iron ions are ferromagnetically ordered within layers, but the coupling between adjacent layers is antiferromagnetic. The presence of vacancies (due to intrinsic non-stoichiometry) in each second layer leads to the appearance of resulting magnetization and ferrimagnetism.
We present phase diagram of the Fe7Se8+Bi2Se3 system. Phase diagram of this system is of simple eutectic type. Coordinates of eutectic point were determined as 80 mol.% Bi2Se3 and 671 °C. Solubility on the base of components is less than 1 mol. %. An eutectic phase Bi2Se3 forms matrix, phase Fe7Se8 – armature. The Bi2Se3 is a leading (seeding) phase, Fe7Se8 - leaded phase. The eutectic Fe7Se8+Bi2Se3 is of a honeycomb type, as far as leading phase Bi2Se3 forms an eutectic matrix.
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Serhii Lakiza |
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H3-VB1448 |
Structural and mechanical properties of SiC-rich by-products of the metal grade Si (MG-Si) process Vira Bovda1,2, Thomas Hafner3, Joans Hafner3, Frank Kimm3, Oleksandr Bovda2, Oleksandr Kuprin2, Anatoliy Pikalov2, Viktoria Podhurska4, Bohdan Vasyliv4, Ihor Vorona5 1MFG Metall- und Ferrolegierungsgesellschaft mbH, Germany, Ukraine The metallurgical grade silicon (MG-Si) has continued to attract much attention as a primary material for photovoltaics, metallurgy, silicones industries etc. The production of MG-Si in submerged electric arc furnaces is accompanied by high-energy consumption and significant carbon and environmental footprint. The traditional solid by-products of the MG-Si process are dross, silica dust, fines and slag. Additionally, dozens of tons of mechanically stable bulk slag are generated inside the Si furnace within its standard life cycle. One of the main components of Si/FeSi furnace slag is silicon carbide (SiC). SiC-rich composites were found in diverse forms and quantities, from loose condensates to sintered crust on the furnace floor that might obstruct the tapping of the liquid Si metal. SiC-rich composites resemble the ceramic materials with a 3D skeleton architecture of hard SiC grains filled with silicone and slag phases.
In this paper, system studies were conducted to assess the correlation between microstructure and mechanical properties of SiC-rich composites produced from the bulk SiC-rich furnace slag by traditional stone and ceramic machining technologies. Macroscopically uniform samples with an area of 50x50mm were composed of coarse monocrystalline SiC grains soaked with Si-rich and glassy cristobalite phases. Dense bulk samples (ρ=3.1 g/cm3) possessed moderate flexural strength in the range of 50-106 MPa and high compression strength of 750 MPa. The fracture mechanism and thermal behaviour of coarse-grained SiC-rich composites was discussed. Despite inhomogeneous macro and microstructure, mechanical and thermal properties of bulk samples are superior to the traditionally produced siliconised SiSiC ceramics. It opens up new opportunity for the circular economy and value-added recycling of the Si/FeSi industries’ wastes.
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Vira Bovda |
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H3-VB1220 |
Ground states in B4C-Al system Oleksandr Vasiliev1, Vladyslav Bilyi1,2, Yaroslav Zaulychnyy2, Valerii Kartuzov1 1Frantsevich Institute for Problems of Materials Science NAS of Ukraine In the last decade, scientists have tried to improve the high-speed impact behavior of boron carbide by doping with silicon and aluminum. The aim of this work is to determine the structure and energies of the ground states in the B4C-Al system and to evaluate their relative stability.We considered the following structures (B₁₂)C^Al^C, (B₁₂)C-Al-C, (B₁₁C)C^Al^C, (B₁₁Al)C-B-C, where aluminum was substituted either into the intercosahedral chain, with or without changing the chain configuration to an angular one, or into a boron carbide icosahedron. The structures were built using the Python ASE library and in-house specialized programs. Parameters of the DFT calculation for the Quantum Espresso software package were chosen to ensure that the total energy converged within 1 meV/atom. The atomic positions and lattice parameters of all structures were optimized with a convergence thresholds of 1.4⋅10⁵ eV on energy and 2.57⋅10² eV/Å on atomic forces. For the optimized configurations the enthalpies of formation were calculated as the difference between the total energy of the structure and total energies of the simple substances and relative stability of the configurations was estimated from their values.(B₁₁Al)C-B-C has a positive formation energy and therefore does not exist. (B₁₁C)C^Al^C has two non-equivalent states with negative but relatively high energy, so it is unlikely to exist. B₁₂C-Al-C configuration has a negative formation energy close to that of B₁₂C-C-C-C and may exist in the material, but it is metastable and readily transforms into an angular configuration. (B₁₂)C^Al^C configuration has 6 degenerate ground states lying in the (0002) plane of a hexagonal prototype cell on a circle with a radius of approximately 1 Å from the center of the intercosahedral chain. This configuration has the lowest energy among all the tested structures, making it the most likely product of boron carbide doping with aluminum.
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Vladyslav Bilyi |
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E-mail: conference@umrs.org.ua