8th International Materials Science Conference HighMatTech-2023
October 2-6, 2023 Kyiv, Ukraine
Composite Materials
Head:
Prof. Iurii Bogomol
PhD, Dr.Sci., Professor Head of department of
High-temperature Materials and Powder Metallurgy
National Technical University of Ukraine
“Igor Sikorsky Kyiv Polytechnic Institute” 37,
Peremohy Ave., 03056 Kyiv, Ukraine
Iurii Bogomol graduated in National Technical University of Ukraine ” Kyiv Polytechnic Institute”. He had short time fellowships in National Institute for Materials Science (Tsukuba, Japan), Nanyang Technological University (Singapore) and Otto von Guericke University Magdeburg (Germany). His scientific interests are: Directional solidification of eutectic alloys, structure and properties of ceramic and metal-ceramic composites based on of refractory compounds; mechanical behaviour of the directionally solidified and SPSed boride and carbide ceramic eutectic composites in wide temperature range. High-entropy alloys based on refractory compounds. He was the manager and coordinator of more than 20 scientific and educational projects. He is author of more than 270 scientific works and patents.
Keynote speaker:
Prof. Petre Badica
Senior Researcher 1st degree
National Institute of Materials Physics, Romania
Badica Petre is a Senior Researcher of 1st degree at NIMP. He graduated in 1992 from University ‘Politehnica’ Bucharest, Romania and was awarded in 1996 a PhD in Engineering Sciences from National Technical University of Ukraine, ‘Kiev Polytechnical Institute’. He is a former JSPS-STA, NIMS, NEDO, MANA, Alexander von Humboldt fellow and Visiting Prof. of Nanyang Technological University, Singapore and Tohoku University, Japan. His interest is in synthesis/processing of materials by conventional and unconventional technologies, advanced complex characterization, and applied physics of selected materials (refractors and structural materials, superconductors, optoelectronic materials and sensors,
biomaterials, archaeometry). He published over 220 ISI articles and 9 book chapters. He acted as co-editor of 1 book and was awarded 5 patents.
Speakers:
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Oral Session |
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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-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 Kirian, Alexander Rud, Andrey Lakhnik G. V. Kurdyumov Institute for Metal Physics of NAS 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 |
Contacts
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E-mail: conference@umrs.org.ua
E-mail: conference@umrs.org.ua