| 摘要 |
PURPOSE:To obtain the titled fine powder useful as starting material for manufacturing a semiconductor treating jig or the like by heating a starting material mixture of specified carbon powder with specified silica powder in a nonoxidizing atmosphere to cause an SiC forming reaction and by removing carbon in the reaction product by oxidation. CONSTITUTION:Carbon powder contg. <=50ppm ashes other than Si and having >=0.1m<2>/g specific surface area is obtd. by removing ashes by heating at 1,600-2,200 deg.C in an atmosphere of gaseous chlorine. The carbon powder is blended with silica powder such as synthetic amorphous silica contg. <=50ppm impurities and having >=0.1m<2>/g specific surface area so as to regulate the molar ratio of C/Si to 3.1-5.0, and they are uniformly mixed to prepare a starting material mixture having 0.03-1.0g/cm<3> bulk specific gravity. The mixture is heated to 1,600-2,000 deg.C at 10 deg.C/min heating rate to cause an SiC forming reaction, this reaction is allowed to proceed until the silica content in the reaction product is lowered to <=1wt%, and carbon in the reaction product is removed by oxidation to obtain the titled fine powder having <=10mum average particle size and >=50% beta-form crystal content and contg. <=2wt% free silica, <=1wt% free carbon and <=100ppm in total of impurities other than free silica, free carbon and water. |
