| 摘要 |
<p>PROBLEM TO BE SOLVED: To industrially produce a transparent quartz glass having a low concn. of impurities in the surface part, contg. no gathered bubbles and having a shape close to that of a jig for the production of a semiconductor as a product at a low cost in a good product yield to starting material. SOLUTION: When a transparent quartz glass is produced by melting silicon dioxide powder in a heat resistant mold, two silicon dioxide powders, that is, crystalline quartz powder and cristobalite powder are used. Layers of the separate powders are allowed to coexist in the mold and melted to separately form molten layers and the molten layers are integrated and made transparent. Natural rock crystal powder is used as the crystalline quartz powder and powder obtd. by perfectly crystallizing amorphous silica powder to cristobalite by heating in the temp. range of 1,200-1,700 deg.C is used as the cristobalite powder.</p> |
