Chemically prestressable aluminosilicate glass and products made therefrom

US5895768A · kind A · utility

Assignee

• Schott Glaswerke · DE

Inventor

• Burkhard Speit · Mainz, DE

Key dates

• Filing date: Apr 25, 1997
• Grant date: Apr 20, 1999
• Expiry date: Apr 25, 2017

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03C3/112
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

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.