| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetic metal powder having high saturation magnetiza tion, excellent in corrosion resistance, dispersibility, remanence ratio, and SFD, and usable for manufacture of a magnetic coating film, its manufacture, and a coating film, containing the magnetic powder, for magnetic recording medium. SOLUTION: In the method of manufacture of the magnetic metal powder, at the time of manufacturing the magnetic metal powder by subjecting pellets of 0.5-20 mm pellet diameter, composed of acicular hydrated iron oxide or acicular iron oxide grains of 0.05-0.25 μm major axis ratio and 4-12 axis ratio, to heating reduction at 400-600 deg.C in a reducing gas, reaction velocity is regulated to (5 to 30)%/hr in the course of reaction at up to 40% reaction ratio. Moreover, in the course of reaction at >=40% reaction ratio, the flow rate of the reducing gas is increased to a value 1.3-50 times the flow rate of the reducing gas in the course of reaction at up to 40% reaction ratio. The magnetic metal powder can be obtained by the above manufacturing method. Further, the coating film for magnetic recording medium contains the magnetic metal powder. |
