The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 09, 2016
Filed:
Mar. 20, 2013
Heraeus Quarzglas Gmbh & CO KG;
Walter Lehmann, Leipzig, DE;
Thomas Kayser, Leipzig, DE;
Heraeus Quarzglas GmbH & Co. KG, Hanau, DE;
Abstract
The production of quartz glass granules comprises the granulation of pyrogenically produced silicic acid and the formation of a SiOgranulate (), the drying and cleaning of the SiOgranulate () by heating in an atmosphere containing halogen, and the vitrification of the SiOgranulate () under a treatment gas which contains at least 30% by volume of helium and/or hydrogen. This process is time-consuming and expensive. In order to provide a method which, starting from a porous SiOgranulate (), allows the cost-effective production of dense, synthetic quartz glass granules suitable for melting bubble-free components of quartz glass, the invention proposes that the cleaning and vitrification of the SiOgranulate () and a post-treatment of the vitrified quartz glass granules are carried out in each case in a rotary tube () of a rotary kiln (), said rotary tube rotating about a central axis (), wherein the rotary tube () comprises an inner wall made of a ceramic material during vitrification, and wherein the vitrified quartz glass granules are subjected to a post-treatment during a treatment period of at least 10 minutes in an atmosphere which contains less than 20% of helium or hydrogen at a treatment temperature of 300° C. or more.