公开(公告)号：DE10349594A1

公开(公告)日：2004-05-13

申请号：DE10349594

申请日：2003-10-24

Applicant: DENSO CORP

Inventor： SUZUKI YASUYOSHI ,  NOMURA YURIO ,  NISHIJIMA YOSHIAKI ,  MIYAKE SHOJI ,  MAKINO YUKIO ,  SATOH TEPPEI

IPC: B22F1/00 ,  B22F1/02 ,  B22F3/105 ,  C22C33/02 ,  H01F41/02 ,  H01F1/22 ,  H01F1/33

Abstract: 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.