| 摘要 |
PURPOSE:To provide a method for producing isotropic graphite material suitable as a crucible for pulling up silicon single crystals and having both of low coefficient of thermal expansion and excellent gas impermeability. CONSTITUTION:50-95 pts.wt. of acicular fine powder having <=15mum average particle diameter is blended with 50-5wt.% of natural graphite fine powder having <=30mum average particle diameter to give a filler raw material and this filler raw material is subjected to kneading treatment with a pitch-based binder and then, the kneaded material is pulverized and the pulverized fine powder is formed by isostatic press (CIP) and subjected to baking and carbonization and subjected to graphitization treatment. Thereby, isotropic graphite material having 2.3-3.8X10<-6>/ deg.C average thermal expansion from room temperature to 1000 deg.C and 0.5-15X10<-2>cm<2>/sec gas permeability is produced. |
