PRODUCTION OF MAGNETIC METALLIC POWDER

PURPOSE:To produce magnetic metallic powder having an excellent magnetic characteristic, narrow grain size distribution width and good dispersibility by subjecting nickel-contg. iron oxyhydroxide formed of hydroxide and carbonate of iron and nickel to a hydrothermal treatment then to reduction by heating. CONSTITUTION:Caustic alkali such as sodium hydroxide is added at about 1-2 times equiv. of ferrous salt to an aq. soln. of the ferrous salt such as ferrous sulfate and nickel salt such as nickel sulfate having about 0.001-0.1 Ni/Fe atomic ratio to effect reaction, thereby forming the hydroxide of iron and nickel. Carbonate such as sodium carbonate is then added at about 1-2 times the equiv. of the hydroxide to said soln. and thereafter an oxygen-contg. gas is supplied at 20-70 deg.C thereto, by which the nickel-contg. iron oxyhydroxide is obtd. The iron oxyhydroxide is then subjected to the hydrothermal treatment at 100-250 deg.C and is then filtered and dried. The dried matter is subjected to reduction by heating to about 350-500 deg.C by a reducing gas such as a gaseous mixture composed of hydrogen and nitrogen by which the metallic powder having the excellent magnetic characteristic such as coercive force, small particle length, narrow grain size distribution width and good dispersibility in formation of paint is thus obtd.