Microstructure and magnetic properties of FeSiCr soft magnetic powder cores with a MgO insulating layer prepared by the sol-gel method

Abstract

In this study, the electromagnetic properties of FeSiCr soft magnetic powder cores (SMPCs) were optimized by providing a novel insulation process. Magnesium acetate tetrahydrate and oxalic acid dihydrate were used as raw materials for the sol-gel method. The powder was then heat-treated at 700 °C so that it was evenly coated by an insulating layer. Thermogravimetric analysis-differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy were used to demonstrate that the layer heat-treated at 700 °C was the ideal MgO layer and was uniformly coated on the surface of the FeSiCr powder. Additionally, the potential reactions and growth mechanism of the MgO layer were analyzed. The effects of the magnesium acetate tetrahydrate content on the soft magnetic properties of the FeSiCr@MgO SMPCs were investigated. The optimal soft magnetic performance (Pcv = 248.48 mW/cm3, measured at 2500 kHz and 10 mT) was achieved at a magnesium acetate tetrahydrate content of 0.50 wt%, yielding a direct current-bias performance of up to 92.3% at 100 Oe. In addition, the FeSiCr@MgO SMPCs effectively improved the heat dissipation performance, which is necessary to avoid high-temperature damage, thereby enhancing their applicability in high-frequency and high-current environments.