Production of acicular magnetic iron oxides
US4136158A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 1, 1977 |
| Grant date | Jan 23, 1979 |
| Priority date | — |
| Expiry date | Nov 1, 1997 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/42
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In the production of acicular ferromagnetic iron oxide of highly uniform particle size by oxidizing an iron (II) hydroxide suspension at a pH of at least 11 with an oxygen-containing gas to form acicular iron (III) oxide hydroxide, reducing and optionally further reoxidizing this into ferromagnetic iron oxide, the improvement which comprises providing the iron (II) hydroxide suspension with a water-soluble silicate in an amount of less than 1.7% by atom based on the amount of the iron (II) hydroxide in the suspension and calculated as the ratio of Si to Fe (II) while prior to the oxidation of the suspension with the oxygen-containing gas.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.