| 摘要 |
PURPOSE:To easily obtain the titled powder having superior strength at high temp. and useful for a heat engine or the like by adding prescribed fine Si3N4 powder contg. beta-phase to mixture of SiO2 powder with C powder and by heat treating them at a high temp. in an atmosphere contg. N2. CONSTITUTION:1pts.wt. SiO2 having <=100mum central particle size and contg. <=0.3wt.% (expressed in terms of metallic elements) in total of impurities such as Al is dry-mixed with 0.005-1pts.wt. fine Si3N4 powder having 15-50m<2>/g BET specific surface area and contg. >=50wt.% beta-phase and 0.4-4 pts.wt. C powder contg. <=0.3wt.% (expressed in terms of metallic elements) in total of impurities such as Al. The mixture is further mixed with 0.0001-0.1pts.wt. (expressed in terms of metallic element) in total of one or more kinds of compds. such as an Mg compd. as required. The mixture is then brought into a reduction nitriding reaction by heating at 1,400-1,600 deg.C for 2-6hr in an atmosphere contg. N2 or the like. The resulting reaction product is heat treatment at 500-800 deg.C for 1-4hr in an oxidizing atmosphere to remove the excess C and to produce fine Si3N4 powder contg. beta-phase.
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