The effect of phosphate/TiO2 composite insulating layer on the high frequency magnetic properties of FeSiBPCNbCu nanocrystalline soft magnetic powder cores

Currently, power electronic devices are developing to meet the requirement of miniaturization, high-frequency and low-power consumption, reducing the high-frequency loss of soft magnetic powder cores (SMPCs) is one of the popular research topics. The construction of multilayer insulating structures can reduce the core loss ( P cv ) of SMPCs by increasing the resistivity. In this work, a composite inorganic insulating layer of phosphate and TiO 2 was successfully synthesized on the powder surface by phosphating and then sol-gel method. At last a nanocrystaline SMPCs with excellent soft magnetic properties were prepared with epoxy resin as the binder. The cores were heat-treated at 510 ℃ for 1 h to achieve optimum soft magnetic properties, with a low P cv of 854 mW/cm 3 at 20 mT and 2 MHz, an effective permeability ( μ e ) of 40 at 10 MHz and excellent DC bias with a percent permeability of 74% of the initial value at 100 Oe. The synergistic effect of the epoxy - TiO 2 - phosphate - nanocrystalline powder multilayer interface effectively reduces inter-particle eddy current loss, resulting in a significant reduction in the P cv of the SMPCs.