Harness, Dickey & Pierce, PLC
Method for producing a soft magnetic material
The invention provides a method for preparing a soft magnetic material which meets demands for low iron loss, high density, high strength and high productivity. The method comprises a surface oxidation step of forming oxide films on the surfaces of a soft magnetic powder, a step of preparing a molding compound of the soft magnetic powder by mixing a soft magnetic powder and a binder with a predetermined blending ratio, a press molding step of press-molding the molding compound of the soft magnetic powder into a predetermined shape, and a sintering step of sintering the press-molded soft magnetic powder to produce a soft magnetic material, wherein a millimeter wave sintering apparatus or a discharge plasma sintering apparatus is used as a heating means in the surface oxidation step or in the sintering step. Thereby, energy of millimeter waves or discharge plasma acts locally on oxidized surface portions having a large electric resistance of the soft magnetic powder, the surfaces of the soft magnetic powder are locally heated at a temperature near the melting point, and oxidation of the surfaces of the soft magnetic powder (formation of an oxide film) and sintering (diffusional joining between oxide films) are promoted.
Denso Corporation
B B B H
B22F B22F B22F H01F
inventional additional inventional inventional
Yasuyoshi Teppei Yurio Yoshiaki Shoji Yukio
Suzuki Satoh Nomura Nishijima Miyake Makino