| 摘要 |
PURPOSE:To obtain a sintered silicon nitride resistant to the deterioration of strength even at high temperature by baking a formed mixture composed of silicon nitride powder, rare-earth metal oxide powder and carbide powder under specific condition. CONSTITUTION:Raw materials composed mainly of silicon nitride powder, rare- earth metal oxide powder and carbide powder are mixed with each other and formed to obtain a formed article. The article is baked in a nitrogen atmosphere at 1700-2100 deg.C under a condition satisfying the formula (0.025x-0.05)<y<=0.1x [x is baking time (hr); y is (weight (g) of the formed article filled in a capsule)/(inner volume (cc) of the capsule)]. The powder of the rare-earth metal oxide is preferably oxide of Y and/or Yb. The carbide powder is preferably e.g. SiC powder of alpha-form, beta-form or amorphous state. |
