POWDER FOR DUST CORE AND PROCESS FOR PRODUCING THE SAME

摘要

A powder for dust cores is provided which comprises a soft-magnetic metal powder having a particle diameter (D), the powder having a silicon-containing layer as a surface layer ranging to less than 0.15D. Also provided is a process for producing the powder. The process comprises subjecting the surface of a soft-magnetic metal powder (1) containing carbon element to a silicon impregnation treatment to produce a powder (10) for dust cores which has a silicon-containing layer (2). The silicon impregnation treatment comprises: bringing a powder for silicon impregnation comprising at least a silicon compound into contact with the surface of the soft-magnetic metal powder (1); heat-treating the powder for silicon impregnation to thereby cause the silicon compound to release the silicon element; and causing the released silicon element to infiltrate and diffuse into a surface layer of the soft-magnetic metal powder. This silicon impregnation treatment is conducted in a release/diffusion atmosphere in which the rate of the reaction in which silicon element is generated by release is higher than the rate of the infiltration/diffusion of the silicon element into the surface layer of the soft-magnetic metal powder.