PROCESS FOR TREATING SYNTHETIC SILICA POWDER AND SYNTHETIC SILICA POWDER TREATED BY THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an economical and efficient process to reduce bubble density and improve bubble stability in a crucible by controlling impurity levels in a synthetic silica powder feed material. SOLUTION: The process for producing a synthetic quartz glass powder which is substantially free of carbon contaminant is provided for the purpose of attaining reduced bubble density and improved stability of an article made from the synthetic quartz glass during fusion molding. In the process, the synthetic silica powder is maintained in an oxidizing environment, e.g. an atmosphere comprising at least 3 vol.% ozone at a temperature of lower than 1400°C, so as to reduce the content of carbon-containing compounds to less than 10 ppm. COPYRIGHT: (C)2006,JPO&NCIPI