Enhancing Magnetic Performance of FeNi50 Soft Magnetic Composites with Double-Layer Insulating Coating for High-Frequency Applications

Soft magnetic composites (SMCs) such as FeNi50 are indispensable in modern electronics due to their high magnetic permeability and low-loss characteristics, meeting the requirements for miniaturization and high-frequency operation. However, the integration of organic materials, initially aimed at reducing the total losses, presents challenges by introducing thermal stability issues at high frequencies. To overcome this obstacle, we propose a double-layer insulating coating method, applying a complete inorganic/organic composite insulation layer to the surface of iron–nickel magnetic powder. The double-layer insulating coating insulation method aims to reduce the total losses, particularly the eddy-current losses prevalent in SMCs. Additionally, the double-layer insulating coating method helps alleviate the thermal stability issues associated with organic materials at high frequencies, ultimately enhancing the magnetic properties of SMCs. We systematically investigated the influence of different resin types on the microstructure of the double-layer insulating coating, accompanied by a comprehensive comparison of the magnetic properties of the resulting samples. The experimental findings demonstrate a significant reduction in the eddy-current losses through the double-layer insulating coating method, with the total losses decreasing by over 95% compared to the initial FeNi50 magnetic powder composite (MPC) materials. Notably, the sodium silicate and silicone resins exhibited superior performances as double-layer insulating coatings, achieving total loss reductions of 1350 W/kg and 1492 W/kg, respectively. In conclusion, the double-layer insulating coating method addresses the challenges related to the total losses and thermal stability in SMCs, offering a promising approach to improve their performance in various electrical and electronic applications.