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:
Mar. 24, 1992
Filed:
Jul. 12, 1989
Applicant:
Inventors:
Assignee:
Thorn EMI plc, London, GB;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01J / ; H01J / ;
U.S. Cl.
CPC ...
313623 ; 313636 ; 501 69 ;
Abstract
A sealing composition is provided for joining crystalline ceramic or cermet parts, e.g. in an arc tube for a discharge lamp. The sealing composition comprises, as starting materials, a mixture of alumina (Al.sub.2,O.sub.3), silica (SiO.sub.2) and magnesia (MgO), the mixture comprising in the ranges of from 22% to 24.5% by weight of Al.sub.2 O.sub.3, from 45.5% to 49.5% by weight of SiO.sub.2, and from 26.0% to 32.5% by weight of MgO. The sealing composition contains less than 40% by weight, of the mixture, of the crystalline phase .alpha.-Cordierite when subjected to the following test procedure.