| 摘要 |
PURPOSE:To solve such a problem that a sintered material has low strength at temp. as high as 1400 deg.C at which a gas turbine engine is used, by adding Al2O3, Y2O3, SiO2, etc., as a sintering assistant for silicon nitride to form an amorphous phase in the intergranular area. CONSTITUTION:A mixture powder is prepared by adding Y2O3 of <=0.5mum average particle size by 2-5wt.% and Al2O3 of <=0.1mum average particle size by between <0.01wt.% and >=0.005wt.% as the sintering assistant to Si3N4 powder of <=0.5mum average particle size and <100ppm total amt. of metal impurities. This mixture powder is molded and sintered at 1650-1800 deg.C in a nonoxidative atmosphere. The obtd. high-temp. high-strength silicon nitride sintered body has >=500MPa four-point bending strength at 1400 deg.C in average. |
