Magnetic recording disc and process for producing the same
US4808455A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 19, 1986 |
| Grant date | Feb 28, 1989 |
| Priority date | — |
| Expiry date | Nov 19, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24999
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An improved magnetic recording disc comprising: a substrate member of an alumina-based ceramic material having micropores of 5 .mu.m or below and having a relative theoretical density of 90% or higher; a glass coating layer of a thickness of 3 to 200 .mu.m with a surface roughness (R.sub.z) of 180 angstroms or below, and being free from micropores and strain; a magnetic thin film formed on the surface of the glass coating layer; and a protective film formed thereon. A process for production of the magnetic recording disc comprises: forming a glass coating layer to a thickness of 5 to 220 .mu.m on the surface of an alumina-based ceramic substrate having micropores of 5 .mu.m or below and a relative theoretical density of at least 90%; then subjecting the glass coating layer to mechanochemical polishing to a layer thickness of 3 to 200 .mu.m, to make free from micropores and strain, and to have a surface roughness (R.sub.z) of 180 angstroms or below; and further coating the surface of the glass coating layer with a magnetic thin film and a protective film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.