Patent · US Expired

Production of gamma iron oxide

US3974079A · kind A · utility

11Cited by

3References

9Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Peter Woditsch · Krefeld, DE
Kurt John Hill · Berthoud, US
Franz Hund · Krefeld, DE
Fritz Rodi · Moers, DE

Key dates

Filing date	Nov 2, 1973
Grant date	Aug 10, 1976
Priority date	—
Expiry date	Nov 2, 1993

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC01P2006/80
WIPO fieldAudio-visual technology
WIPO sectorElectrical engineering

Abstract

Process for producing ferromagnetic iron oxides whereby a solution of a ferrous salt is oxidized in the presence of .alpha.-FeO(OH) seed, a basic precipitant, and phosphoric acid or a water soluble salt thereof to form .alpha.-FeO(OH), which can be dehydrated, optionally tempered, reduced and re-oxidized to needle-shaped .gamma.-Fe.sub.2 O.sub.3. The resulting product has high coercive force values which make it especially useful for magnetic impulse recording and reproduction.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.