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 (Pcv) of SMPCs by increasing the resistivity. In this work, a composite inorganic insulating layer of phosphate and TiO2 was successfully synthesized on the powder surface by phosphating and then sol-gel method. At last a nano-crystaline SMPCs with excellent soft magnetic properties were prepared with epoxy resin as the binder. The cores were heat-treated at 510 celcius for 1 h to achieve optimum soft magnetic properties, with a low Pcv of 854 mW/cm3 at 20 mT and 2 MHz, an effective permeability (mu 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 -TiO2 -phosphate -nanocrystalline powder multilayer interface effectively reduces inter-particle eddy current loss, resulting in a significant reduction in the Pcv of the SMPCs.