PRETREATMENT OF QUARTZ GLASS MOLDING VESSEL

摘要

PURPOSE:To obtain a quartz glass molding vessel wherein moldability and yield of a molded article are improved by coating silica sol-silicon carbide slurry on the surface of a molding vessel made of graphite. CONSTITUTION:Silica sol-silicon carbide slurry is coated on the surface of a molding vessel made of graphite which is used to obtain a molded body having a required shape by pressurizing and molding quartz glass at high temp. Then a silicon carbide layer is formed on the surface of this molding vessel by heat- treating the molding vessel coated with this slurry. In order to prepare the used silicon sol-silicon carbide slurry, preferably ion-exchange water is firstly added in reactive equivalent to organic silicon e.g. silicon compd. forming silica sol by hydrolysis such as tetraethoxysilane to form silica sol slurry. Then high- purity beta-silicon carbide fine powder is added to this slurry in the range of Si(OH)4/SiC=1.0-0.10 molar ratio to obtain silica sol-silicon carbide slurry.