SYNTHETIC QUARTZ GLASS POWDER, QUARTZ GLASS MOLDED MATERIAL THEREOF, AND EVALUATION OF THE SYNTHETIC QUARTZ GLASS POWDER

摘要

PROBLEM TO BE SOLVED: To provide a synthetic quartz glass powder suppressed in devitrification in using a melt-molded material at a high temperature. SOLUTION: This synthetic quartz glass powder is obtained by baking silica gel powder derived from hydrolysis of alkoxysilane. When the powder is vacuum-melted at 1,780-1,800 deg.C and resultant ingot is further kept at 1,630 deg.C for 5hrs, a number of white devitrified spots having a size of >=20μmϕgenerated in the ingot is <=10pieces/50g.