| 摘要 |
PURPOSE:To obtain the sintered body having an excellent high-temp. characteristic by specifying the silicon nitride content in silicon nitride powder, the kind and quantity of an oxide to be added as a sintering assistant, a calcination temp., and a gaseous pressure. CONSTITUTION:A mixture formed by adding the oxide of >=1 kinds of group IIIa elements of >=0.1% silicon oxide content to silicon nitride powder contg. 0.5 to 4.0wt.% silicon oxide is prepd. This mixture is calcined until the bulk density attains >=95% theoretical density in a nitrogen atmosphere of 5 to 200atm. pressure and 1800 to 2000 deg.C. Since the oxide of the compsn. having excellent heat resistance and oxidation resistance is formed at the grain boundaries by this method, the sintered body which is not only excellent in ordinary temp. strength but is also extremely less degraded in the strength at a high temp., is excellent in the oxidation resistance and is excellent in the high-temp. characteristics, such as creep resistance characteristic, high-temp. strength, heat resistance and oxidation resistance, is obtd. |
