Fundamental Study on Relationship between High-Frequency Magnetic and Mechanical Properties of Soft Magnetic Composites and Chemical Structure of Insulation Polymer Treated under Various Annealing Conditions

This study investigated the high-frequency magnetic properties under 1 MHz and 3 mT, as well as the mechanical characteristics of soft magnetic composites and the chemical structure of the insulation polymer treated under various annealing conditions. Among the iron particles comprising the soft magnetic composites, Fe-6.5Si powder and dimethylpolysiloxane were utilized as the soft magnetic powder and insulation polymer, respectively. The organic components of the insulating resin in the composites heat-treated at temperatures above 673 K degraded; however, the degradation of inorganic components was not observed under infrared spectroscopy even at 873 K. Although the composite underwent moderate mechanical deterioration due to the structural change of the resin from heat treatment, the electrical resistivity of the composite heat-treated at 873 K was reduced to 1/100th of that of the composite heat-treated at 573 K. Despite the significant reduction in electrical resistivity, the core loss did not increase under the given excitation conditions.