PURPOSE: To provide magnetic powders with sufficiently large coercive force and improve saturated magnetic flux density, by a method wherein Co, Ni or the like is adhered to iron oxyhydroxide with specified major axis length and minor axis lenght or to that doped by Co, Ni or the like, and then reduction is performed in a reducing gas atmosphere.
CONSTITUTION: Iron oxyhydroxide such as α-FeOOH having mean major axis length of 0.2W2μm perferably 0.5W1.5μm and mean minor axis length of 0.01W 0.1μm preferably 0.03W0.08μm, iron oxide such as α-Fe2O3, and doped substance of metal such as Ni, Co or alloy thereof onto above-mentioned iron oxyhydroxide or iron oxide are used. Hydroxide or oxide of Co, Ni is adhered, adsorbed or deposited to iron oxyoxide or iron oxide and the surface coating treatment is performed. The treated substance is dried and then reduced in a reducing gas atmosphere such as hydrogen at a temperature of 600°C or less. In this constitution, magnetic powders are obtained at iron content 70W98wt% and coercive force of 160Oe or more.
MORIYA YOSHIMI
KOMA YOSHISHIGE
TAKANO KATSUHIRO
| JPS563605A | 1981-01-14 | |||
| JPS5673408A | 1981-06-18 |