PRODUCTION OF MAGNETIC PARTICLE POWDER OF ACICULAR CRYSTAL METAL CONSISTING ESSENTIALLY OF METALLIC IRON

摘要

PURPOSE:To produce titled particle powder consisting essentially of metallic iron having excellent oxidation stability by reducing acicular crystal ferric oxide particles under heating and treating the particles to an immersion treatment in an org. solvent then treating the particles in an aq. soln. contg. ferrous hydroxide under adequate conditions. CONSTITUTION:Acicular crystal ferric oxide particles consisting essentially of Fe2O3 are used as a starting material and are reduced in a reducing gas under heating. The particles consisting essentially of the resulting metallic iron are subjected to an immersion treatment in an org. solvent and are dried at 20-50 deg.C after filtration. The dried particles are dispersed into an aq. soln. contg. ferrous hydroxide. The dispersion thereof is treated in a non-oxidative atmosphere in the range of 0.05-3.0mol/l concn. of an OH group and 50-100 deg.C. A magnetite film is formed on the particle surfaces by such treatment, by which the particles can be safely taken out into air and the decrease in the saturation magnetization sigmas owing to oxidation in the air is prevented. The magnetic particle powder of the acicular crystal metal consisting essentially of the metallic iron having excellent oxidation stability is obtd.