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:
Sep. 01, 1987
Filed:
Jul. 26, 1985
Applicant:
Inventors:
Assignee:
Sumitomo Special Metals Co., Ltd., Osaka, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01F / ; B05D / ; B32B / ;
U.S. Cl.
CPC ...
428 64 ; 428409 ; 428432 ; 428698 ;
Abstract
A substrate member for recording disk characterized in that a glass coating film is provided on an alumina base ceramic material having micropores of no larger than 5 microns and a relative theoretical density of no less than 96%, said glass coating film having a surface roughness of no more than 80 angstroms, being substantially pore-free and strain-free on the surface, and having a thickness of 0.3 to 200 microns and a relative difference of no more than 10.sup.-6 /deg in the coefficient of thermal expansion with respect to said base material.