PURIFICATION OF RAW MATERIAL POWDER FOR QUARTZ GLASS

摘要

PURPOSE:To obtain transparent quargz glass free from foams, by heat-treating raw material powder for quartz glass in an atmosphere of a halide vapor alone such as sulfuryl halide, thionyl halide, etc. or in a mixed atmosphere of the vapor and an inert gas at a given temperature. CONSTITUTION:A calcination furnace is charged with an atmosphere of vapor of one ore more of halides such as sulfuryl halide, thionyl halide, and silicone halide or a mixed atmosphere of the vapor and an inert gas. A raw material for quartz glass such as rock crystal, silica is added to the furnace, and heat- treated at 700-1,700 deg.C. Consequently, impurities and OH group are removed from the raw material, and a transparent quartz glass free from foams is obtained.