| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject material reduced in core loss and having superior DC superimposing characteristic by subjecting a mixture consisting of an alloy powder composed essentially of Fe, Al, and Si and a binder to compression molding and then to heat treatment in an oxidizing atmosphere. SOLUTION: It is preferable that a surface oxide film on an alloy powder is <=100 nm thick and/or Al content in an alloy is 5-10%. Heat treatment temperature is 500-900 deg.C, at which hysteresis loss can be reduced and also an oxide layer can be formed on the surface of the alloy powder. Preferred average particle size of the alloy powder is <=100 μm. By the heat treatment in an oxidizing atmosphere, an oxide (alumina) layer is formed in the broken part of an insulating layer on the surface of the alloy powder at the time of compression molding. As a result, insulation between the alloy powder particles can be secured to reduce overcurrent loss, and accordingly, core loss can be reduced, and simultaneously, respective alloy powder particles can be insulated with certainty to uniformize the distance between the alloy powder particles, and superior DC superimposing characteristic can be attained. |
