High temperature process for making fine magnetic particles
US4777031A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 14, 1986 |
| Grant date | Oct 11, 1988 |
| Priority date | — |
| Expiry date | Jul 14, 2006 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/42
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention is a method of producing single, unaggregated magnetic iron oxide particles. An iron or iron and divalent metal halide feed solution is kinetically atomized into a high velocity flame. The feed solution is vaporized and held in a reactor at a temperature and partial pressure of an oxidizing phase sufficient to form either ferrous oxide or magnetite particles. The iron or iron and divalent metal halide vapor reacts with the oxidizing phase vapor and converts to either ferrous oxide vapor or magnetite vapor. Since the vapor phase is beyond equilibrium concentration ferrous oxide or magnetite particles precipitate from the vapor phase. Quenching of the magnetite particles at an enhanced rate to less than 500.degree. C. in a reducing atmosphere renders magnetite and in a oxidizing atmosphere renders maghemite. Quenching of the ferrous oxide particles in a non-oxidizing atmosphere produces magnetite particles.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.