Denso Corporation

Masataka Mitomi

Seishi Utsuno

Jung Hwan Hwang

Ken Matsubara

Tomoyasu Watanabe

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 powder for dust core used for a dust core includes a plurality of crystal grains, and the powder has at least two maximal values when a number ratio that is a ratio of the number of the crystal grains at each crystal grain diameter to the number of the crystal grains each crystal grain diameter of which has been measured is plotted with respect to each crystal grain diameter of the crystal grains.

Growing community of inventors

Kariya, Japan

Masataka Mitomi