DUST CORE AND POWDER FOR MAGNETIC CORE

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PROBLEM TO BE SOLVED : To provide a dust core that can achieve both a high specific resistance and a high magnetic flux density at a very high level. SOLUTION : The present invention is a dust core formed of soft magnetic particles formed of pure iron or an iron alloy and grain boundary layers present between the adjacent soft magnetic particles, and the grain boundary layer has an insulating layer having a garnet ferrite crystal structure. Specifically, the insulating layer is formed of R3Fe5O12 (R : rare earth element). R3Fe5O12 is represented by Y3Fe5O12. A part of R may be substituted with Ca, Nd, Pr and the like. Such a dust core is obtained by press molding a powder for a magnetic core obtained by covering the surface of the soft magnetic particles having a particle diameter of 50 to 500 μm with Y3Fe5O12 particles having a particle diameter of 25 to 500 nm. The dust core of the present invention exhibits, for example, high characteristics in which when an applied magnetic field is 5 kA/m, the magnetic flux density (B5K) becomes 1.45 T or more, and the specific resistance becomes 500 μΩm or more. SELECTED DRAWING : Figure 2 COPYRIGHT : (C)2019, JPO&INPIT