Borosilicate glass of greater resistance to chemical attack and applications thereof

US6204212A · kind A · utility

Assignee

• Schott Glas · DE

Inventors

• Christian Kunert · Wiesbaden, DE
• Peter Brix · Mainz, DE

Key dates

• Filing date: Sep 16, 1999
• Grant date: Mar 20, 2001
• Expiry date: Sep 16, 2019

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03C3/093
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The zirconium-containing and lithium-containing borosilicate glasses have a higher resistance to chemical attack and have the following composition (in % by weight on an oxide basis): SiO.sub.2, 71 to <73%; B.sub.2 O.sub.3, 7 to 10%; Al.sub.2 O.sub.3, 6 to 9%; Li.sub.2 O, 0.5 to 2%; Na.sub.2 O, 0 to 10%; K.sub.2 O, 0 to 10%; MgO, 0 to 2%; CaO, 0 to 3%; SrO, 0 to 3%; BaO, 0 to 3%; ZnO, 0 to 3%; ZrO.sub.2, 0.8 to 3%; CeO.sub.2, 0 to 1%, and a refining agent in an amount suitable for refining, as needed, with the proviso that a total amount of Li.sub.2 O+Na.sub.2 O+K.sub.2 O is from 0.5 to 10.5%, and with the proviso that a total amount of MgO+CaO+SrO+BaO+ZnO is from 0 to 3%. These borosilicate glasses with their thermal expansion coefficients .alpha..sub.20/300 between 5.2 and 5.7.times.10.sup.-6 /K are especially suitable for sealing glasses for Fe--Co--Ni alloys.