| 摘要 |
PURPOSE:To easily and inexpensively manufacture a cubic BN composite sintered compact by blending respective powders of amorphous BN, metals such as Mg, etc., and hard materials such as carbides, etc., in a specific ratio and by sintering the resulting mixture at and under the high temp. and high pressure under proper conditions. CONSTITUTION:The amorphous BN powder (55-75% by volume), the principal metal powder (5-15%) of <=700 deg.C melting point, such as Mg, Sb, Sn, etc., and the hard material powder (40-10%) of carbides, borides, nitrides, silicides, oxides, etc., are mixed to be formed into a starting material for sintering. The above material is heated until 700 deg.C is reached under a sintering pressure of 33,000-61,000kg/cm<2>, so that above-mentioned principal metal powder is melted. Then, heating is intensified with applying hydrostatic pressure to other powder grains via the above molten principal metal and the temp. and pressure conditions in the cubic BN-stabilized region are satisfied, so that individual amorphous BN grains are subjected to transition into cubic BN grains. In this way, the molten principal metal applies liquid-phase sintering to the cubic BN grains and hard material grains. This liquid phase sintered compact is cooled down to 300 deg.C, so that cubic BN composite sintered compact suitable for super hard tool material of solid phase sintered compact can be obtained.
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