Denso Corporation

Toyota Jidosha Kabushiki Kaisha

Kabushiki Kaisha Toyota Chuo Kenkyusho

Seishi Utsuno

Jung Hwan Hwang

Ken Matsubara

Kazuaki Haga

Fumitaka Yoshinaga

Yuji Kaneko

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 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

There is provided a method for manufacturing a soft magnetic member where a coating formed of an &#x3b1;-FeOsingle phase having a high electrical resistivity is formed on a soft magnetic alloy substrate. A soft magnetic alloy substrate is heated in an atmosphere containing water vapor and inert gas to form a coating on the soft magnetic alloy substrate. The atmosphere has an oxygen partial pressure in a range of 0 to 1.5 kPa. A soft magnetic member including the soft magnetic alloy substrate and the coating formed on its surface can be obtained.

Method for manufacturing soft magnetic member

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.

Powder for dust cores, method for producing same, dust core and method for producing dust core

A ferrite powder according to the present invention includes a laminar structure exhibiting a state where W-type ferrite phases are laminated in an easy direction of magnetization, the W-type ferrite phases including a compound expressed by AMFeO, where A, M, Fe, and O represent a first metal element (Sr, Ba, Ca, Pb, etc), a second metal element (Fe, Zn, Cu, Co, Mn, Ni, etc), iron, and oxygen, respectively. This ferrite particle is obtained through: a shape forming step that shapes a mixed powder in a magnetic field to obtain a compact, the mixed powder including for example an M-type ferrite particle including a compound expressed by AFeOand a spinel-type ferrite particle (S-type ferrite particle) including a compound expressed by MFeO; a calcination step that calcines the compact to obtain a calcined substance; and a milling step that mills the calcined substance.

Growing community of inventors

Nagakute, Japan

Seishi Utsuno