Reducing melt borosilicate glass having improved UV transmission properties and water resistance and methods of use

US5610108A · kind A · utility

Assignee

• Schott Glaswerke · DE

Inventors

• Eckhart Watzke · Jena, DE
• Thomas Kloss · Jena, DE
• Peter Brix · Mainz, DE
• Franz Ott · Mitterteich, DE

Key dates

• Filing date: Oct 7, 1994
• Grant date: Mar 11, 1997
• Expiry date: Oct 7, 2014

Classification

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

Abstract

Reducing melt borosilicate glass having a UV transmittance of at least 85% for ultraviolet radiation having a wavelength of 254 nm for a sample thickness of 1 mm and a water-resistance of less than 100 micrograms, advantageously less than 62 micrograms, Na.sub.2 O per gram of glass powder according to ISO 719 and a thermal expansion coefficient .alpha..sub.20/300 of from 5 to 6.times.10.sup.-6 K.sup.-1 and comprising from 58 to 65% by weight SiO.sub.2, from 18 to 20.5% by weight B.sub.2 O.sub.3, from 8.1 to 10.4% by weight Al.sub.2O.sub.3, from 0 to 1% by weight CaO, from 0 to 2% by weight BaO, from 0 to 2% by weight SrO, from 0 to 1.5% by weight Li.sub.2 O, from 5.5 to 8.5% by weight Na.sub.2 O, from 0 to 3% by weight K.sub.2 O and from 0 to 2% by weight fluorine. The sum total content of all of the alkali metal oxides present in the glass is not greater than 10% and the sum total content of the CaO, BaO and SrO is not greater than 3% and the molar ratio of Al.sub.2 O.sub.3 : Na.sub.2 O is from 0.6 to 1. The glass is particularly suitable for EPROM windows, UV lamps, photomultipliers, spectrophotometers under difficult climatic conditions and protective tubes for UV lamps immersed…