High-Frequency Electromagnetic Properties of Injection Molded Soft Magnetic Composites

Soft magnetic composites mean ferromagnetic powder coated by an electrical insulation layer, which is often used for high-power electromagnetic applications. In this work, toroidal magnetic cores such as FeSiAl and FeNi were fabricated by injection molding, and the electromagnetic properties were studied. Magnetic hysteresis loops of composite samples were measured at 25 and 100 °C to study the change of saturation magnetization and coercivity at room temperature and operating temperature. Effective permeability values of magnetic cores were between 8.8 and 18.9, and they were relatively stable within the frequency range of 70 MHz. Each kind of magnetic core shows low power loss at the frequency range of 100 kHz to 1 MHz, and the power loss of FeSiAl core was as low as 168 mW/cm 3 at 1 MHz and 20 mT. DC bias permeability of all samples exceeded 70% at a bias field of 300 Oe. Compared with the high-pressure molded core, the injection magnetic cores have lower power loss and good DC bias characteristics, which are beneficial to the application of high frequency and high current.