A process for the preparation of a ferromagnetic metal powder, and the use of the powder for magnetic recording materials

摘要

A process for preparing a ferromagnetic metal powder and a magnetic recording medium utilizing that powder are disclosed. The ferromagnetic metal powder is prepared by heat-treating an acicular iron oxyhydroxide or an acicular iron oxide powder prepared from the acicular iron oxyhydroxide in a non-reducing gas at a temperature of from 300° C. to 1000° C. or in a reducing gas at a temperature of from 150. degree. C. to 500° C. The heat-treated material is washed and then reduced under heating. The ferromagnetic metal powder prepared in this manner is dispersed in a binder and cated on a non-magnetic base to form a magnetic recording medium. By utilizing the washing step followed by heat-treating preparing the ferromagnetic metal powder a large amount of water soluble impurities are removed from the metal powder. The metal powder produced according to this disclosed process as excellent oxidation stability and ability to resist corrosion. Accordingly, the magnetic recording medium prepared utilizing this powder has an excellent ability to resist oxidation and corrosion even when subjected to adverse conditions.