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AssigneesNational Institute of Advanced Industrial Science and Technology, Denki Kagku Kogyo Kabushiki Kaisha
InventorsKiyoshi Hirao, Shuji Sakaguchi, Yukihiko Yamauchi, Shuzo Kanzaki, Suzuya Yamada
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A boron carbide based sintered body having a four-point flexural strength of at least 400 MPa and a fracture toughness of at least 2.8 MPa·m1/2, which has the following two preferred embodiments. (1) A boron carbide-titanium diboride sintered body obtained by sintering a mixed powder of a B4C powder, a TiO2 powder and a C powder while reacting them under a pressurized condition and comprising from 95 to 70 mol % of boron carbide and from 5 to 30 mol % of titanium diboride, wherein the boron carbide has a maximum particle diameter of at most 5 μm. (2) A boron carbide-chromium diboride sintered body containing from 10 to 25 mol % of CrB2 in B4C, wherein the sintered body has a relative density of at least 90%, boron carbide particles in the sintered body have a maximum particle diameter of at most 100 μm, and the abundance ratio (area ratio) of boron carbide particles of from 10 to 100 μm to boron carbide particles having a particle diameter of at most 5 μm, is from 0.02 to 0.6.
A process for producing a boron carbide-titanium diboride sintered body comprising mixing a titanium dioxide powder having an average particle diameter of less than 1 μm and a carbon powder having an average particle diameter of less than 1 μm to a boron carbide powder having a maximum particle diameter of at most 5 μm, an average particle diameter of at most 1 μm and a specific surface area of at least 10 m2/g, heating the mixture to a temperature of 1000° C. under a pressure of from 2.0×10−1 to 2.0 10−1 to 2.0 10−2 Pa and sintering the mixture within a temperature range of from 1900 to 2100° C. while reacting them under a pressurized condition of at least 20 MPa.
Dependencies are inferred from the claim text.