Process for production of pure transparent quartz
AssigneesTosoh Corporation, Nippon Silica Glass Co., Ltd.
InventorsKoichi Orii, Yukinobu Hara, Tomoyuki Akiyama, Koji Tsukuma, Yoshikazu Kikuchi
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Abstract
Pure transparent quartz glass is provided by molding powdery amorphous silica into an article, converting the molded powdery amorphous silica into crystalline silica of high-temperature type cristobalite structure, and then fusing the crystalline silica, the quartz glass containing impurities respectively at a content of not higher than 1 ppm, and an OH group at a content of not higher than 20 ppm, and having a viscosity of 10.sup.12.0 poise or more at 1200.degree. C. The quartz glass is transparent and has high purity, and is excellent in high temperature viscosity characteristics. The quartz glass can be produced at a low cost.
Claims5
A process for producing pure transparent quartz glass, comprising steps of molding powdery amorphous silica into an article, converting the molded powdery amorphous silica in a vacuum or a helium atmosphere into crystalline molded silica of high-temperature cristobalite structure, and then fusing the crystalline silica into glass, wherein the molded silica is converted into the crystalline silica without addition of any crystallization promoter.
Dependencies are inferred from the claim text.