| 摘要 |
PURPOSE:To provide ferromagnetic powder by a method wherein gamma-Fe2O3 and its partially reduced iron oxide magnetic powder are added to an aqueous alkaline solution which contains Co salt, and dispersed, then, after treated at temperatures higher than room temperature, soluble silicon compound is added and treated. CONSTITUTION:In water medium, CoCl2 and its equivalent or more of alkali are added to acicular gamma-Fe2O3 and magnetic powder provided by partial reduction of the above alpha-Fe2O3 and which is in an intermediate form between Fe2O3 and Fe3O4. The CoCl2 and alkali are dissolved and dispersed respectively, then maintained over room temperature to allow Co-containing iron oxide to form on the surface of powder. Thereafter, soluble silicon compound is added and treated. Applicable silicon compound includes hardly soluble one, ortho- or meta-silicic acid, metallic salt thereof such as sodium orthosilicate, silica gel, water glass. This constitution can provide ferromagnetic powder. |
