| 摘要 |
PURPOSE:To produce a composite ceramic material having high strength and high toughness. CONSTITUTION:A composite ceramic material is produced by subjecting a powdery mixture composed mainly of alpha-silicon nitride powder and beta-silicon carbide powder to the primary sintering and then to the secondary sintering at a temperature higher than the primary sintering temperature under a nitrogen partial pressure higher than the nitrogen partial pressure in the primary sintering step. In the above process, the sum of the total impurity oxygen in the alpha-silicon nitride powder and the beta-silicon carbide powder is adjusted to 1.0-1.5wt.%, the total impurity carbon content is adjusted to 0.25-0.40wt.% and the length of the matrix silicon nitride in the direction of the major diameter is made to be <=11.0mum. |
