| 摘要 |
PROBLEM TO BE SOLVED: To obtain a dust core having high permeability and a high-frequency characteristic by extrusion-molding flaky soft magnetic metal powder into a plate-like shape. SOLUTION: Flaky powder having lengths of 40μm and an average thickness of 2μm, and aspect ratio of about 20 is obtained by crushing an Fe-Si-Al alloy ingot with a disk mill and grinding the crushed pieces in a ball mill for 50 hours. Then, a raw molding material is obtained by mixing a silicone resin and stearic acid with the flaky powder at a mixing ratio of 93:6:6 in wt.% and kneading the mixture for 30 seconds with a pressure kneader and the raw material is pelletized. Then, the pelletized raw material is extrusion-molded into platy bodies having thicknesses of 0.50, 1.4, 7, 10, and 13 mm by means of an extrusion-molding machine by using a mold, which has a width of 20 mm and a variable width at a molding temperature of 200 deg.C. Thereafter, a dust core is obtained by punching each obtained molded body into a toroidal shape of 15 mmϕ×10 mm and heat-treating the punched body at 700 deg.C for two hours. Therefore, the permeability and high-frequency characteristics of the dust core can be improved.
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