| 摘要 |
PURPOSE:To easily and surely produce the sintered silicon nitride body having high strength at an ordinary temp. and high temp. by mixing silicon nitride powder, mullite powder and aluminum nitride powder, molding the mixture and heating and sintering the molding in a nonoxidative atmosphere. CONSTITUTION:A) 90 to 99.2wt.% silicon nitride powder (the powder is usually of an alpha type and may contain a beta-phase. grain size: adequately 0.1 to 1mum), B) sintering assistant: 1) mullite (the mullite consisting of 71.6 to 72.0wt.% Al2O3, 28.0 to 28.4% SiO2 and having >= 99.9% purity is optimum, grain size: preferably about equal to the grain size of Si3N4 or below) and 2) AlN (particle size: preferably about equal to the grain size of Si3N4 or below), are mixed at 0.8 to 10% in total of 1), 2) (the mixing ratio is preferably >=0.4% each) and after the mixture is molded to a prescribed shape, the molding is heated and sintered to 1700 to 1800 deg.C in the nonoxidative atmosphere, by which the sintered Si3N4 body is obtd. |
