PURPOSE: To obtain the title magnetic core having high permeability and low iron loss using the magnetic metal powder, on which surface treatment is carried out with silicon Alkyd, as raw material magnetic powder.
CONSTITUTION: The surface of magnetic metal powder is coated with silicon alkoxide, the power is heated up in the temperature range of 200 to 700°C in an oxidizing atmosphere, and a silicon oxide film, which is grown by decomposition and oxidization of silicon alkoxide, on the surface of the magnetic metal powder. For example, tetraethoxysilane is diluted with ethanole by a factor of 2, and atomized iron powder is mixed therein. This mixture is heated up, cooled in the furnace, and power of raw material is obtained. To be more precise, the frequency (μ-f) characteristics of the initial permeability of the tetraethoxysilane-treated atomized iron powder in the implementation example 1 and the non-treated material in the comparison example 1 are compared. As a result, the μ of the material of the implementation example 1 does not decrease to 5MHz or thereabout, and μ-f characteristics can be improved clearly.