| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide metal powder for a dust core in which high insulation properties are maintained even when, for increasing the electric resistance between each powders, the amount of insulated coating applied to the surface of the powder is remarkably reduced or is made zero, and thus both of high saturated magnetic flux density and high electric resistance are improved. Ž<P>SOLUTION: Pure iron powder having grain size of 10 to 500 μm and purity of ≥99 mass% is heated to the temperature range of 600 to 1,000°C, Si is concentrated on the surface of the pure iron powder in the above temperature range by vapor phase reaction, the average Si concentration in the depth range from the surface to 1 μm of the concentrated layer is controlled to 0.05 to 2 mass%, and thereafter, an Si oxide layer with a thickness of 1 to 500 nm is formed on the surface of the powder by oxidation treatment. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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