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:
Jan. 08, 2013
Filed:
Jun. 29, 2009
Walter Lehmann, Leipzig, DE;
Achim Hofmann, Frankfurt, DE;
Thomas Kayser, Leipzig, DE;
Heraeus Quarzglas GmbH & Co. KG, Hanau, DE;
Abstract
A method of producing a quartz glass crucible for pulling a single crystal comprising: providing a melting mold comprising a wall having passages between outside and inside; providing an outer layer granulation consisting of first coarser SiOparticles and forming an outer granulation layer from the outer layer granulation on the inside of the melting mold wall; providing a barrier layer granulation consisting of second finer SiOparticles and forming a barrier granulation layer from the barrier layer granulation on the outer granulation layer; applying a negative pressure to the outside of the melting mold wall; and heating the barrier granulation layer and the outer granulation layer with formation of a quartz glass crucible with transparent inner layer. In order to produce a sealing layer that is as thin and uniform as possible it is suggested that the SiOparticles of the barrier layer granulation should have a mean particle size (Dvalue) of less than 50 μm and that the formation of the barrier granulation layer should include a measure for fixing the barrier layer granulation to the outer granulation layer.