Precipitated alumina for use in magnetic recording disc media
US4404238A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 16, 1981 |
| Grant date | Sep 13, 1983 |
| Priority date | — |
| Expiry date | Apr 16, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/265
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A magnetic recording medium and method of producing the same are taught. The medium comprises magnetic particles and alumina particles dispersed in a binder as a unitary coating whereby each of the alumina particles disposed in the binder is substantially equal to the thickness of the medium wherein the alumina particles are produced by first forming an aluminum hydrate from alumina hydrate gel according to the following equation: EQU Al.sub.2 O.sub.3.nH.sub.2 O.fwdarw.Al.sub.2 O.sub.3.3H.sub.2 O+(n-3)H.sub.2 O and heating the aluminum hydrate above approximately 800.degree. C. to form alumina of substantially spherical configuration according to the following equation: EQU Al.sub.2 O.sub.3.3H.sub.2 O.fwdarw.Al.sub.2 O.sub.3 +3H.sub.2 O
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.