Method for the continuous production of a tube or rod of vitreous fused silica

US4923497A · kind A · utility

Assignee

• Heraeus Quarzschmelze GmbH · DE

Inventors

• Helmut Leber · Hanau, DE
• Nigel Whippey · Seligenstadt, DE

Key dates

• Filing date: Feb 17, 1989
• Grant date: May 8, 1990
• Expiry date: Feb 17, 2009

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S65/09
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

A method for the continuous production of a tube or rod of vitreous fused silica. Silicon dioxide in particle form is heated in a crucible to the softening temperature and is withdrawn contiuously downward from a bottom outlet opening in which a shaping tool is disposed. In the annular space between the shaping tool and the bottom outlet opening the softened silicon dioxide is subjected to an electrical field. In the closed crucible, a hydrogen-containing atmosphere with a hydrogen content of at least 80% is sustained above the silicon dioxide and in the space underneath the crucible that adjoins the shaping region.