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. 28, 1989
Filed:
Oct. 14, 1986
Sumitomo Special Metals Co., Ltd., Osaka, JP;
Abstract
A process for producing a substrate member for magnetic recording disc with improved surface state free of defects such as micropores and strain due to machining, and improved surface roughness, such substrate being obtained by first forming a glass coating layer on the surface of a substrate of an alumina-based ceramic material containing therein micropores of 5 .mu.m or less and having a relative theoretical density of 90% or above; then, subjecting the glass coating layer on a substrate to the hot isostatic pressing treatment; and further subjecting the surface of the glass coating layer to mechanochemical polishing to a layer thickness in a range of from 3 .mu.m to 200 .mu.m and the surface free from micropores and strain. Glass coating may be done by glazing or vapor deposition like sputtering.