PURPOSE: To obtain superior ferromagnetic metal powder by the adhesion of at least one of borate, phosphate, silicate and molybdate of an element of group IIa, to powder of oxide or hydroxide of iron or metals consisting essentially of iron, and by reducing the mixture.
CONSTITUTION: Iron oxide grains or goethite grains are dispersed in a solution containing at least one (designated A here) of borate, phosphate, silicate, molybdate and tangustate, and a solution of a water-soluble IIa group element salt B is added to this solution to form on the grain surface a uniform film of insoluble or hard-to-dissolve salt (such as calcium borate, calcium silicate and coprecipitates of water-soluble salts A, B, etc.). These metal oxide grains, after filtering, washing and drying, are reduced by heating in reducing gas to obtain metal powder. IIa group elements used here include Be, Mg, Ca, Sr and Ba. Because sintering between grains during heating reduction can be prevented in this constitution, metal powder with a desirable grain shape is obtainable. This powder also has high coercive force, a large amount of saturation magnetization, and is moisture- and oxidation-resistant.
KAWADA TAKAKO
KIMURA KAZUO
MIYAHARA TETSUSHIYUU
DAINIPPON INK RIKAGAKU KENKUYS
| JPS5613411A | 1981-02-09 | |||
| JPS5230758A | 1977-03-08 |