초록 ▼

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 powd

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.

대표청구항 ▼

The invention claimed is: 1. 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 carbi

The invention claimed is: 1. 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. 2. The process for producing a boron carbide based sintered body according to claim 1, wherein the specific surface area of the boron carbide powder is at least 16 m2/g, and the average particle diameter of each of the titanium dioxide powder and the carbon powder is less than 0.1 μm. 3. The process of claim 1, wherein said pressurized condition is from 30 to 100 MPa. 4. The process of claim 1, wherein said pressurized condition is from 30 to 60 MPa.