Patent · US Expired

Manufacture of .gamma.-iron(III) oxide

US4061727A · kind A · utility

6Cited by

3References

8Claims

0Family size

Assignee

BASF SE

Inventors

Guenter Vaeth · Schifferstadt, DE
Manfred Ohlinger · Bischofswerda, DE
Heinz Stritzinger · Ludwigshafen, DE
Eduard Schoenafinger
Eugen Wettstein · Germersheim, DE
Wolfgang Guth

Key dates

Filing date	Oct 15, 1976
Grant date	Dec 6, 1977
Priority date	—
Expiry date	Oct 15, 1996

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC01P2006/42
WIPO fieldAudio-visual technology
WIPO sectorElectrical engineering

Abstract

Acicular .gamma.-iron(III) oxide is manufactured by reacting an iron(II) salt solution with aqueous solutions of alkali metal hydroxides and oxidizing the resulting suspension of iron(II) hyroxides in 3 stages. In the first stage not more than 8 percent by weight of the iron(II) hydroxide originally present is oxidized over a period of 0.5 to 4 hours, in the second stage from 25 to 55 percent by weight over a period of 1.5 to 6 hours and the remainder thereof in a third stage. Following this oxidation, the goethite formed is reduced to magnetite, which is then oxidized to acicular .gamma.-iron(III) oxide.

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