PURPOSE: To prepare a cobalt-containing ferromagnetic iron oxide, by treating a magnetic iron oxide with an alkali and an aqueous solution of a cobalt salt and a ferrous salt to effect the coating of the iron oxide with a cobalt-containing metallic compound, and carrying out the steam treatment and heat treatment of the product at a specific low temperature.
CONSTITUTION: Magnetic iron oxide is treated with an aqueous solution of a Co salt and a ferrous salt and/or other metallic salt, and an alkali, at about ≤50°C to apply a Co-containing metallic compound to the surface of the iron oxide particle. The magnetic iron oxide s e.g. γ-Fe2O3, etc., the Co salt is e.g. cobalt chloride, etc., and its amount is about 0.5W30wt% based on the iron oxide. The ferrous salt is e.g. ferrous chloride, etc., and its amount is about 1W30wt%. The other metallic salt is, e.g. an Mn salt, etc., and its amount about is 0W10wt%. The coated iron oxide is treated with steam at 60W200°C, and then heat treated in an inert atmosphere at 100W250°C. By this process, a Co-containing ferromagnetic iron oxide having high coercive force, and excellent square ratio, orientation, and saturated flux density can be obtained by low temperature treatments.
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NAKADA KAZUO
ISHIKAWA TSUNEO
HONMA ICHIROU
KOYAMA ARATA
AMANO MASATOSHI
| JPS54106895A | 1979-08-22 | |||
| JPS5135697A | 1976-03-26 | |||
| JPS50119997A | 1975-09-19 |