PRODUCTION OF SILICON NITRIDE CERAMIC SINTERED BODY

摘要

PURPOSE:To increase the strength of a molded body and to produce a large- sized or complex-shaped product by using powdery starting material prepd. by adding a specified amt. of powder of silicon nitride whiskers to silicon nitride powder having a specified alpha-phase content and a specified particle size when the molded body is produced by casting. CONSTITUTION:Powdery starting material consisting of 1-50wt.% powder of silicon nitride whiskers and the balance silicon nitride powder having >=90wt.% alpha-phase content and <=1.0mum average particle size is slurried and this slurry is defoamed and cast into a molded body of a prescribed shape with a gypsum mold of a prescribed shape. The resulting ceramic molded body has a low coefft. of contraction by drying and cracks hardly. The molded body is then sintered in a nonoxidizing atmosphere to obtain a silicon nitride ceramic sintered body having superior mechanical characteristics.