| 摘要 |
PURPOSE:To obtain the titled sintered material having high strength and free from sintering shrinkage, by forming a powdery mixture of Si3N4 powder, silicon powder and a compound of group IIIa element of the periodic table and baking the formed article under a specific condition. CONSTITUTION:A formed article is produced by forming a powdery mixture of (A) 40-80wt.% of Si3N4 powder having an average particle diameter of <=0.6mum, (B) 20-45wt.% of silicon powder having a purity of >=99% and an average particle diameter of <=50mum and (C) 0.5-15wt.% of a compound of group IIIa element of the periodic table (e.g. Y2O3) by press forming, casting, extrusion forming, etc. The formed article is sintered at 1,150-1,400 deg.C for 15-50hr in a pressurized nitrogen gas of 2-10atm. until >=90% of silicon is converted into nitride. The product is densified by sintering again at 1,700-2,100 deg.C in nitrogen atmosphere under pressure of gas. |
