| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing spindlelike alloy magnetic grain powder essentially consisting of Fe and Co for magnetic recording which has high coercive force and high saturation magnetization value in spite of the small size of crystallites advantageously from the industrial and economical phases. SOLUTION: Spindlelike goethite grains of 0.05 to 0.15 μm major axis size contg. cobalt of 20 to 45 atomic % expressed in terms of Co to the whole Fe or spindlelike hematite grains obtd. by subjecting the goethite grains to dehydration under heating are used as a starting raw material, this starting raw material is charged into a fixed layer reducing device to form a fixed layer of <=30 cm layer height, thereafter, its temp. is raised to the temp. range of 400 to 700 deg.C in an inert gas atmosphere, next, it is changed over to a reducing gas atmosphere, and, after that, the starting raw material is reduced in the temp. range of 400 to 700 deg.C by reducing gas in which gas superficial velocity is 40 to 150 cm/s. |
