Process for stabilizing ferromagnetic chromium dioxide
US4374118A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 5, 1981 |
| Grant date | Feb 15, 1983 |
| Priority date | — |
| Expiry date | Nov 5, 2001 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/42
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
This invention relates to a process for stabilizing ferromagnetic chromium dioxide in respect of water and oxidizable organic compounds which it may contact in magnetic tapes. The process is applicable to a starting CrO.sub.2 having good magnetic properties, i.e. a coercive force not lower than about 400 Oersted, a maximum magnetic induction B.sub.m not lower than about 2500 gauss, and a magnetic induction B.sub.r not lower than about 1600 gauss. The CrO.sub.2 is subjected to a heat treatment at a temperature ranging from 300.degree. to 390.degree. C. in the presence of a gas stream not exerting any oxidizing or reducing action on the compounds of trivalent, tetravalent and hexavalent chromium. Suitable gases are, for example, nitrogen, helium and argon.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.