Borosilicate glass weak in boric acid

US5599753A · kind A · utility

Assignee

• JENAer Glaswerk GmbH · DE

Inventors

• Eckhart Watzke · Jena, DE
• Andrea Kampfer · Jena, DE
• Thomas Kloss · Jena, DE
• Gerhard Kemmler · Jena, DE

Key dates

• Filing date: Aug 30, 1995
• Grant date: Feb 4, 1997
• Expiry date: Aug 30, 2015

Classification

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

Abstract

Borosilicate glass weak in boric acid having a high chemical stability with an alkali resistance according to DIN 52 322 of LBK-Class 1, a thermal expansion .alpha..sub.20/300 between 4.0 to 5.3.times.10.sup.-6 K.sup.-1, a ratio .alpha.'/.alpha. of thermal expansion coefficients above T.sub.g (.alpha.') to below T.sub.g (.alpha.) of 4 to 8, a glass transformation temperature between 500.degree. C. and 600.degree. C., high radiation transmittance and a UV transmission .tau..sub.250 nm/1 mm of 0 to 70% or .tau..sub.300 nm/1 mm of 0 to 91% of the composition in percent by weight on oxide basis of: SiO.sub.2 >75; B.sub.2 O.sub.3 1 to <9; Al.sub.2 O.sub.3 3 to 6; Li.sub.2 O 0 to 4; Na.sub.2 O 0 to 8; K.sub.2 O 0 to 6; MgO 0 to 3; CaO 0 to 3; BaO 0 to 2; SrO 0 to 2; ZnO 0 to 3; ZrO.sub.2 0 to 3; SnO.sub.2 0 to 3; SnO 0 to 3; TiO.sub.2 0 to 2; CeO.sub.2 0 to 2; Fe.sub.2 O.sub.3 0 to 1; with SiO.sub.2 +B.sub.2 O.sub.3 >83; SiO.sub.2 :B.sub.2 O.sub.3 >8; SiO.sub.2 +Al.sub.2 O.sub.3 +ZrO.sub.2 >83; Li.sub.2 O+Na.sub.2 O+K.sub.2 O 5 to 10; MgO+CaO+BaO+SrO+ZnO>3.