Sintering and properties of ultrahigh-temperature composites with silicon-containing additives

DOI: 10.62564/M4-AL1170

Anastasiia Lokatkina¹, Tetiana Prikhna¹, Pavlo Barvitskyi¹, Viktor Moschil`¹, Olexander Borimskyi¹, Serhiy Rychev¹, Myroslav Karpets², Semyon Ponomarev³, Anatoliy Bondar², Leonid Devin<sup>1

1</sup>V. Bakul Institute for Superhard Materials of the National Academy of Sciences of Ukraine
²Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine
³V. Lashkaryov Institute of Semiconductor Physics of National Academy of Science of Ukraine


Materials containing transition metals such as Zr, Hf, Ta, Mo, W, or Nb in conjunction with B, C or N are deemed ultrahigh temperature materials. Our research UHTCs centers on composites founded on ZrB2, ZrC, HfB2, HfC and their solid solutions, with an expanded array of properties compared to existing materials. An elevated level of mechanical and damping characteristics is achieved through strong interconnectivity between grain phases due to use starting nanopowders and high and moderate pressures. These ceramic composites show promise for use as construction and wear-resistant materials in high-temperature environments. In order to reduce cracking and fragility of the obtained composites, our work also considered the use carbon- and silicon-containing additives that initiate the formation of laminar structures in the materials. It is known that the interfaces between the layers and the different nature of the 1st and subsequent layers give the structure of the material the ability to quench cracks [1]. Since it is known that the addition of silicon can be used to reduce the consolidation temperature of UHTM, as well as to increase the mechanical stability [2] of such materials by dissolving silicon in the matrix structure [3], we employed silicon-containing additives (MoSi2, Si3N4, ZrSi2 and SiC) in study. We used hot pressing (30 MPa) and high pressure/temperature techniques – recessed-anvil HPA (4.1 GPa, due 1800 oC) when compacting samples. For example, HP samples HfC – 10, 20 and 30 wt.% MoSi2 were characterized by microhardness (HV49) up to 18.7, 19.5 and 22.1 GPa respectively, and density 10.82, 11.03 and 11.46 g/cm3 respectively. Thus, when we used 20 wt.% MoSi2 to ZrB2, it was possible to reduse the sintering temperature at HP to 1700 oC (more than 200 degrees), and the material showed a microhardness of about 23.7 GPa at density 5.86 g/cm3. At both, composites significantly exceeded pure materials results, at the same conditions synthesizing.

Keywords
ultra-high temperature materials, composites, hot pressing, HIP, mechanical characteristics

Acknowledgments
Not provided

References
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