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:
Apr. 20, 1999
Filed:
Apr. 25, 1997
Burkhard Speit, Mainz, DE;
Schott Glaswerke, Mainz, DE;
Abstract
The chemically prestressable glass having a low bubble count and bubble size has the following composition in mol %, based on a total amount of oxides present, SiO.sub.2 from 63.0 to 67.5 mol %, Al.sub.2 O.sub.3 from 9.5 to 12.0 mol %, Na.sub.2 O from 8.5 to 15.5 mol %, K.sub.2 O from 2.5 to 4.0 mol %, MgO from 3.0 to 9.0 mol %, sum of CaO+SrO+BaO+ZnO from 0 to 2.5 mol %, TiO.sub.2 from 0.5 to 1.5 mol %, CeO.sub.2 from 0.02 to 0.5 mol %, As.sub.2 O.sub.3 from 0.02 to 0.35 mol %, SnO.sub.2 from 0. to 1.0 mol %, and F.sub.2 from 0.05 to 2.6 mol %, wherein the molar ratio �SiO.sub.2 !/�Al.sub.2 O.sub.3 ! is 5.3 to 6.85, the molar ratio �Na.sub.2 O!/�K.sub.2 O! is 3.0 to 5.6, the molar ratio �Al.sub.2 O.sub.3 !/�K.sub.2 O! is 2.8 to 3.6 and the molar ratio �Al.sub.2 O.sub.3 !/�TiO.sub.2 +CeO.sub.2 ! is 7.6 to 18.5, but, when arsenic-free, SnO.sub.2 is from 0.02 to 1.0 mol % and F.sub.2 is from greater than 0.5 to 2.6 mol %. The invention also includes a safety glass and a hard disk for information storage made from this chemically prestressable glass.