Denso Corporation

Ken Matsubara

Seishi Utsuno

Jung Hwan Hwang

Makoto Taniguchi

Akira Fukushima

Satoshi Doi

Masataka Mitomi

A dust core that can significantly reduce the iron loss is provided. The dust core of the present invention includes soft magnetic particles comprising pure iron or an iron alloy and a grain boundary layer existing between adjacent soft magnetic particles. The grain boundary layer has a compound layer comprising MFeSiO(0&#x2264;x&#x2264;1, M: one or more types of metal elements that serve as divalent cations). Such a dust core is obtained by annealing a compact. The compact is obtained by compression-molding a powder for magnetic cores. In the powder for magnetic cores, coating layers that coat the surfaces of soft magnetic particles are each composed of a composite phase in which spinel-type ferrite represented by MFeO(0&#x2264;y&#x2264;1, M: one or more types of metal elements that serve as divalent cations) is dispersed on a surface of a silicone resin or inside the silicone resin. The dust core after annealing exhibits a high specific resistance due to the grain boundary layer having the compound layer and can reduce both the eddy-current loss and the hysteresis loss.

Compressed powder magnetic core, powder for magnetic core, and production methods therefor

A rotary electrical machine is equipped with a rotor that is rotatably supported, and a stator having a stator core that is disposed coaxially with the rotor. The stator core is configured as a plurality of stacked steel plates, and has a yoke portion that is of annular shape, a plurality of teeth extending radially from the yoke portion, and slots between adjacent teeth. A stator winding is wound in the slots. The yoke portion has holes that extend in the stacking direction of the steel plates, at positions of radial-direction extension of the slots, and molded powder bodies formed from a magnetic powder are provided within the holes.

Rotary electrical machine with stator core having powder bodies within holes

A dust core including soft magnetic particles having pure iron or an iron alloy and a grain boundary layer present between adjacent soft magnetic particles. The grain boundary layer has a main phase and a barrier phase. The main phase having a spinel-type ferrite of a metal element. The metal element serves as a divalent cation. The barrier phase having one or more of Cu, Sn, or Co. The dust core can be obtained by using a powder for magnetic cores including soft magnetic particles coated with a film in which a first ferrite and a second ferrite coexist. The barrier phase blocks the Fe diffusion from the soft magnetic particles and suppresses the deterioration of the main phase having the second ferrite responsible for the insulating property.

Dust core, powder for magnetic cores, and methods of manufacturing them

A powder for dust cores includes an aggregate of soft magnetic particles, each of which includes a soft magnetic metal particle, and a ferrite film that covers a surface of the soft magnetic metal particle and includes ferrite crystal grains having a spinel structure. A diffraction peak derived from the ferrite crystal grains exists in a powder X-ray diffraction pattern. By a method for producing a powder for dust cores, a raw material powder that includes an aggregate of soft magnetic metal particles is prepared. Furthermore, many ferrite fine particles are formed on a surface of each of the soft magnetic metal particles of the raw material powder. Additionally, the ferrite fine particles are coarsely crystallized through heat treatment to form a ferrite film, which includes ferrite crystal grains having a spinel structure, on the surface of the each of the soft magnetic metal particles.

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Kariya, Japan

Ken Matsubara