| 摘要 |
PURPOSE:To produce the title sintered body having excellent strength and oxidation resistance at high temp. and having high toughness by compacting the starting material contg. Si3N4 powder, the compd. of a group IIIa element, and excess oxygen, heat-treating the compact at a specified temp., and further subjecting the heat-treated compact to the hot hydrostatic press sintering at a specified temp. CONSTITUTION:The three-component mixed powder contg. 85-95mol.% Si3N4, 0.5-5mol.% of the compd. (oxides are most preferable) of an element (M) (e.g., Sc, Er, and Yb) selected from group IIIa elements, expressed in terms of an oxide (M2O3), and excess oxygen and wherein the molar ratio of the excess oxygen expressed in terms of SiO2 to the M2O3 is controlled to >=1 is used as the starting material and compacted. The compact is heat-treated at 1,550-1,850 deg.C. The heat-treated compact is subjected to the hot hydrostatic press sintering at 1,650-2,000 deg.C. By this method, the title sintered body having excellent strength and oxidation resistance at high temp. and having high toughness can be obtained. |
