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|Section2= |Section3= |Section4= |Section7= |Section8= }} Zirconium carbide (ZrC) is an extremely hard refractory ceramic material,〔Measurement and theory of the hardness of transition- metal carbides , especially tantalum carbide. Schwab, G. M.; Krebs, A. Phys.-Chem. Inst., Univ. Muenchen, Munich, Fed. Rep. Ger. Planseeberichte fuer Pulvermetallurgie (1971), 19(2), 91-110〕 commercially used in tool bits for cutting tools. It is usually processed by sintering. ==Properties== It has the appearance of a gray metallic powder with cubic crystal structure. It is highly corrosion resistant. This Group IV interstitial transition-metal carbide is also a member of ultra high temperature ceramics or (UHTC). Due to the presence of metallic bonding, ZrC has a thermal conductivity of 20.5 W/m·K and an electrical conductivity (resistivity ~43 μΩ·cm), both of which are similar to that for zirconium metal. The strong covalent Zr-C bond gives this material a very high melting point (~3530 °C), high modulus (~440 GPa) and hardness (25 GPa). ZrC has a lower density (6.73 g/cm3) compared to other carbides like WC (15.8 g/cm3), TaC (14.5 g/cm3) or HfC (12.67 g/cm3). ZrC seems suitable for use in re-entry vehicles, rocket/SCRAM jet engines or supersonic vehicles in which low densities and high temperatures load-bearing capabilities are crucial requirements. Like most carbides of refractory metals, zirconium carbide is sub-stoichiometric, i.e., it contains carbon vacancies. At carbon contents higher than approximately ZrC0.98 the material contains free carbon.〔 ZrC is stable for a carbon-to-metal ratio ranging from 0.65 to 0.98. ZrC reacts with water and acids and is pyrophoric. The mixture of zirconium carbide and tantalum carbide is an important cermet material. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Zirconium carbide」の詳細全文を読む スポンサード リンク
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