Abstract: The invention provides a method for manufacturing a soft magnetic powder material covered by oxide layers at surfaces of the powder, by using a soft magnetic alloy powder containing a soft magnetic powder material and a second element such as Si having an oxidizing reactivity higher than iron, and heating the soft magnetic alloy powder in an atmosphere of a weak oxidizing gas by mixing a weak oxidizing gas in an inert gas, and oxidizing selectively the second element at surface layers of the powder while restraining an oxidation of iron to form thin oxide layers with high electrical resistance.

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.

Abstract: A first core is formed by stacking a plurality of magnetic plates of a soft magnetic material, such as iron, in a direction perpendicular to a plane of each magnetic plate. A bonding thin layer made of iron oxide having a thickness of approximately a few nanometers to a few hundred micrometers is formed between adjacent ones of the magnetic plates. The adjacent magnetic plates are bonded to each other by diffusion bonding in such a manner that the bonding thin layer is interposed between the adjacent magnetic plates to electrically insulate between the adjacent magnetic plate.

Abstract: A first core is formed by stacking a plurality of magnetic plates of a soft magnetic material, such as iron, in a direction perpendicular to a plane of each magnetic plate. A bonding thin layer made of iron oxide having a thickness of approximately a few nanometers to a few hundred micrometers is formed between adjacent ones of the magnetic plates. The adjacent magnetic plates are bonded to each other by diffusion bonding in such a manner that the bonding thin layer is interposed between the adjacent magnetic plates to electrically insulate between the adjacent magnetic plate.