| 摘要 |
PURPOSE:To obtain the subject product having improved strength by preparing a raw material composed of Si3N4 powder, rare-earth metal oxide powder, SiC powder and powder of a W compound and/or Mo compound, forming the raw material and baking the formed article in N2 atmosphere. CONSTITUTION:Si3N4 powder having high alpha-content is mixed with (A) 2.7-10mol% of rare-earth metal oxide such as Y2O3 and/or Yb2O3, (B) 0.5-11wt.% (outer percentage, based on the sum of Si3N4 and the rare-earth metal oxide) of SiC powder and (C) 0.5-3wt.% (outer percentage, based on the sum of Si3N4 and the rare-earth metal oxide) of a W compound selected from metal, carbide, oxide and silicide of W and/or an Mo compound selected from metal, carbide, oxide and silicide of Mo. The obtained mixture is pulverized, the powdery mixture is formed in a prescribed form and the formed article is baked at 1700-2100 deg.C under normal or positive pressure and cooled at a cooling rate of <=100 deg.C/min to obtain sintered Si3N4 having crystallized intergranular phase. |
