Method and apparatus for the production of flat, transparent vitreous silica slabs of low bubble content

US4475204A · kind A · utility

Assignee

• Heraeus Quarzschmelze GmbH · DE

Inventors

• Lutz Brandt · Maintal, DE
• Karl Kreutzer · Leverkusen, DE
• Karlheinz Rau · Hanau, DE
• Horst Schmidt · Bad Endbach, DE
• Fritz Simmat · Gelnhausen, DE

Key dates

• Filing date: Sep 13, 1982
• Grant date: Oct 2, 1984
• Expiry date: Sep 13, 2002

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03B5/0334
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

Flat, transparent slabs of vitreous silica of optical quality are produced by melting granular starting material in a vacuum by means of an electrical heating system. The starting material is melted while sustaining a heat flow from the top to the bottom of the crucible. The bottom of the crucible is made permeable to gases. The heat isolation power of the crucible wall increases from the bottom to the top of the crucible.