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:
Feb. 08, 1983
Filed:
May. 05, 1981
Masayuki Kaneno, Tokoname, JP;
Takehiro Kajihara, Komaki, JP;
NGK Insulators, Ltd., Nagoya, JP;
Abstract
A polycrystalline translucent alumina sintered body having high in-line transmission, which is suitable for an envelope for a high pressure vapor discharge lamp, is produced by adding to alumina powder having a purity of more than 99.8% MgO or a compound forming MgO in an amount of 0.01-0.1% by weight calculated as MgO, La.sub.2 O.sub.3 or a compound forming La.sub.2 O.sub.3 in an amount of 0.001-0.05% by weight calculated as La.sub.2 O.sub.3, and Y.sub.2 O.sub.3 or a compound forming Y.sub.2 O.sub.3 in an amount of 0.001-0.5% by weight calculated as Y.sub.2 O.sub.3, thoroughly mixing the resulting mixture, shaping the mixture into a desired form and firing the shaped article under vacuum or either atmosphere of hydrogen gas or dissociated ammonia gas under oxygen concentration of 10.sup.-15 -10.sup.-25 atm.