| 摘要 |
PURPOSE:To make it possible to prevent mechanical breakage with needle fracture of ferromagnetic metal powder by a method wherein metal compound grain is dipped into a solution containing an aluminum compound in a specific steeple device. CONSTITUTION:The metal compound grain mainly composed of iron or ferrous compound is reduced by heating in a reducing atmosphere, and the ferromagnetic metal powder mainly composed of iron or a ferrous compound is obtained. An aluminum compound is coated on the surface of the metal compound grain by dipping the metal compound grains into the solution containing an aluminum compound before a reducing operation is conducted. A steeple type device, having the diameter D and height H0 of the ratio in the range of 0.5-50, is used and the aluminum compound is coated while the solution is being mixed by circulating gas from the bottom part of the device. As a result, the mechanical breakage with needle fracture of ferromagnetic metal powder can be prevented. |
