Boron carbide based sintered compact and method for preparation thereof
a boron carbide and compact technology, applied in the field of boron carbide based sintered compact, can solve the problems of low strength, drawbacks of inability to obtain boron carbide sintered body flexural strength at least 600 mpa, and achieve excellent characteristics, high strength, and improved fracture toughness
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examples 1 to 40
[0061] As boron carbide powders, specific boron carbide powders A, B and C having the physical properties as identified in Table 1, were employed. As a submicron-size titanium dioxide powder, one having an average particle diameter (D50 as measured by a laser diffraction scattering analyzer) of 0.3 μm and a crystal phase of rutile type, was used. Further, as a nano-size titanium dioxide powder, a spherical powder prepared by a gas phase method and having a specific surface area (BET) of 48.5 m2 / g, an average particle diameter (BET method) of 31 nm and a crystal phase of 80% anatase and 20% rutile, was used. As a carbon powder, carbon black having a specific surface area (BET) of 88.1 m2 / g and an average particle diameter (BET method) of 30 nm, was used.
TABLE 1Physical properties of boron carbide powdersAverageMaximumB4C startingparticleparticlematerialdiameterdiameterBETpowderμmμmm2 / gA0.502.421.5B0.443.315.5C0.412.322.5D0.555.718.7E1.205.98.6
[0062] To the boron carbide powder, 14....
example 5
[0068] To a boron carbide powder I having the physical properties as identified in Table 3, 20 mol % of a chromium diboride powder having an average particle diameter (D50) of 3.5 μm was blended, and using a methanol solvent, the blend was mixed by a planetary ball mill made of SiC at a rotational speed of 275 rpm for 1 hour. The slurry was dried by an evaporator and further dried at 150° C. for 24 hours, and then it was sieved through a sieve of 250 mesh to obtain a boron carbide-chromium diboride mixed powder.
[0069] This powder was molded in a mold under 20 MPa, followed by CIP molding under 200 MPa to obtain a molded product. The molded product was put into a graphite container and placed in a resistance heating type firing furnace. Heating was carried out at a temperature-raising rate of 40° C. / min while vacuuming to a pressure of from 2.0×10−1 to 2.0×10−2 Pa by means of a diffusion pump. When the temperature reached 1000° C., vacuuming was terminated, and Ar gas was introduced...
example 6
[0072] To a boron carbide powder II having the physical properties as identified in Table 3, 20 mol % of a chromium diboride powder having an average particle diameter (D50) of 3.5 μm was blended, and using a methanol solvent, the blend was mixed by a planetary ball mill made of SiC at a rotational speed of 275 rpm for 1 hour. The slurry was dried by an evaporator and further dried at 150° C. for 24 hours, whereupon it was sieved through a sieve of 250 mesh to obtain a boron carbide-chromium diboride mixed powder.
[0073] This powder was molded in a mold under 20 MPa, followed by CIP molding under 200 MPa to obtain a molded product. The molded product was put into a graphite container and placed in a resistance heating type firing furnace. Heating was carried out at a temperature-raising rate of 40° C. / min while vacuuming to a pressure of from 2.0×10−1 to 2.0×10−2 Pa by means of a diffusion pump. When the temperature reached 1000° C., vacuuming was terminated, and Ar gas was introduc...
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