The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 02, 1999
Filed:
Nov. 25, 1997
Tatsuhiro Sato, Takefu, JP;
Akira Fujinoki, Koriyama, JP;
Kyoichi Inaki, Koriyama, JP;
Nobumasa Yoshida, Koriyama, JP;
Tohru Yokota, Koriyama, JP;
Shin-Etsu Quartz Products Co., Ltd., Fukui, JP;
Abstract
Opaque silica glass having a density of 2.0 to 2.18 g/cm.sup.3, sodium and potassium elements concentrations in the silica glass of each 0.5 ppm or less and an OH group concentration of 30 ppm or less, and containing bubbles which are independent bubbles having the following physical values: a bubble diameter of 300 .mu.m or less, and a bubble density of 100,000 to 1,000,000 bubbles/cm.sup.3, and a production process for opaque silica glass, including: filling quartz raw material grain having a particle size of 10 to 350 .mu.m in a heat resistant mold, heating it in a non-oxidizing atmosphere from a room temperature up to a temperature lower by 50 to 150.degree. C. than a temperature at which the above raw material grain is melted at a temperature-raising speed not exceeding 50.degree. C./minute, then, slowly heating it up to a temperature higher by 10 to 80.degree. C. than the temperature at which the quartz raw material grain is melted at the speed of 10.degree. C./minute or less, and cooling after maintaining at the above temperature.