| 摘要 |
PROBLEM TO BE SOLVED: To obtain silica glass powder with slight bubbling when melted, useful for ultra-high-purity products, by grinding and drying a silica gel produced by hydrolyzing an alkoxysilane, effecting a specific liquid content of the silica gel whose particle distribution is also regulated so as to remove isolated silanol at low-temperature baking. SOLUTION: This silica glass powder is obtained by the following process: an alkoxysilane such as tetramethoxysilane is hydrolyzed using about 1-10 equivalent times of water; the resulting gel is ground and dried into silica gel powder <=50 wt.% in liquid content; thereafter, the silica gel powder is subjected to ultrasonic sieve or wet classification to reduce particles of <=45μm size to <=1 wt.% (pref. about <=0.5 wt.%) content; the resulting silica gel powder is then baked, pref. through the following procedure: the silica gel powder is held at 300-600 deg.C or so once to sufficiently reduce the carbon levels therein followed by heat treatment at 1,000-1,300 deg.C or so in a dry gas atmosphere with a dew point of about <=-200 deg.C.
|
