| 摘要 |
PURPOSE:To form raw material powder of Si3N4 for sintering having a low residue ratio of pores on the surface layer of sintered material, thin discolored layer of surface and small variability of density, strength and hardness of sintered material by limiting the specific surface area of raw material powder of Si3N4 and an average oxygen amount thereof in specific ranges. CONSTITUTION:This raw material powder of Si3N4 has 9.5 to 11.0m<2>/g specific surface area of powder particles thereof and 1.00 to 1.50wt.% average oxygen amount contained in the powder particles. In order to sinter the abovementioned raw material powder of Si3N4, the following two methods are used. (1) The raw material powder of Si3N4 or powder comprising raw material powder of Si3N4 further and a sintering auxiliary is molded, presintered and the presintered material is sintered by hot isotropic hydrostatic press or (2) the raw material powder of Si3N4 or the powder comprising raw material powder of Si3N4 further and a sintering auxiliary is molded, the molded article is covered with glass capsules and sintered by hot hydrostatic press. |
