PURPOSE: To produce magnetic metallic powder having excellent corrosion resistance, magnetic characteristic, etc. by diffusing the magnetic metallic powder into water and bringing said metallic powder in to contact with the dissolved oxygen in the water while interrupting the supply of oxygen into the water thereby oxidizing the surface of said powder.
CONSTITUTION: An org. solvent such as the toluene which is insoluble in water, has the specific gravity smaller than the specific gravity of water, dissolves hardly oxygen and is inert to the above-mentioned metallic powder is impregnated in the magnetic metallic powder of iron, etc. obtd. by reduction and the powder is charged into water. Then the above-mentioned org. solvent floats in the water and covers the surface thereof, thus interrupting the supply of oxygen into the water. The water is maintained preferably at about ≤30°C and the above-mentioned metallic powder is immersed therein for about ≤3hr so as to contact with the dissolved oxygen in the water, thereby forming the oxide film on the surface of the metallic powder. The magnetic metallic powder having the excellent corrosion resistance, magnetic characteristic and dispersibility in a binder is obtd. by such treatment.
ISHIGURO TAKASHI
TATSUNO TETSUO
