UV-transparent glass

US5045509A · kind A · utility

Assignee

• Schott Glaswerke · DE

Inventor

• Werner Kiefer · Ingelheim am Rhein, DE

Key dates

• Filing date: Jan 19, 1989
• Grant date: Sep 3, 1991
• Expiry date: Jan 19, 2009

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S501/905
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The invention relates to a glass which is transparent to UV radiation and which, for a thickness of 1 mm and the wavelength of 253.7 nm has a transmission of at least 75%, a linear coefficient of thermal expansion of 3.8.times.10.sup.-6 to 4.5.times.10.sup.-6 K.sup.-1 in the temperature range from 20.degree. to 300.degree. C. and a hydrolytic resistance of <120 .mu.g of Na.sub.2 O/g according to DIN 12 111. The new glass has the synthesis composition, calculated on an oxide basis, of ______________________________________ SiO.sub.2 64 to 66.5 percent by weight B.sub.2 O.sub.3 20 to 22.5 percent by weight Al.sub.2 O.sub.3 4 to 6 percent by weight Li.sub.2 O 0.4 to 1 percent by weight Na.sub.2 O 1.0 to 3.5 percent by weight K.sub.2 O 1.0 to 2.5 percent by weight CaO 0.35 to 0.8 percent by weight BaO 0.5 to 2.0 percent by weight F.sup.- 0.5 to 2.0 percent by weight .SIGMA. Li.sub.2 O + Na.sub.2 O + K.sub.2 O 3.8 to 5.5 percent by weight .SIGMA. CaO + BaO 1.0 to 2.5 percent by weight one or more 0.2 to 2.0 percent by weight non-oxidizing refining agents one or more 0.05 to 0.3 percent weight. reducing agents ______________________________________