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:
Jun. 18, 2002
Filed:
Aug. 31, 2001
Hiroya Nagata, Atsugi, JP;
Masayuki Kudo, Machida, JP;
Koji Tsukuma, Tsukuba, JP;
Yoshikazu Kikuchi, Sagae, JP;
Tomoyuki Akiyama, Yamagata, JP;
Other;
Abstract
An opaque silica glass article comprising a transparent portion and an opaque portion, wherein the opaque portion has an apparent density of 1.70-2.15 g/cm and contains 5×10 -5×10 bubbles per cm , said bubbles having an average diameter of 10-100 &mgr;m; and the transparent portion has an apparent density of 2.19-2.21 g/cm and the amount of bubbles having a diameter of at least 100 &mgr;m in the transparent portion is not more than 1×10 per cm. The opaque silica glass article is made by a process wherein a mold is charged with a raw material for forming the opaque portion, which is a mixture comprising a silica powder with a small amount of a silicon nitride powder, and a raw material for forming the transparent portion so that the two raw materials are located in the positions corresponding to the opaque and the transparent portions, respectively, of the silica glass article to be produced; and the raw materials are heated in vacuo to be thereby vitrified.