Enhancing soft magnetic properties of FeSiBNbCu nanocrystalline powder cores by coating ZrO2 insulation layer

The insulation coating plays a crucial role in minimizing core loss (Pcv) in soft magnetic powder cores (SMPCs). In this work, we prepared ZrO2 coating layer on FeSiBNbCu spherical powder by the hydrolysis-precipitation method and investigated the magnetic properties of the FeSiBNbCu@ZrO2 nanocrystalline SMPCs. ZrO2 coating layer were successfully fabricated on the powder by adding a proper amount of K2ZrF6 in alkaline ethyl alcohol solution. The micromorphology and chemical structure of the ZrO2 coating layer on the surface of FeSiBNbCu nanocrystalline powder, as well as the conversion mech-anisms, has been investigated. The presence of the ZrO2 coating reduces the Pcv by significantly lowers eddy loss (Pe) of the nanocrystalline SMPCs, meanwhile improves DC bias performance and slightly decreases their permeability. When the additive amount of K2ZrF6 is 1.0 wt%, the nanocrystalline SMPCs has best comprehensive soft magnetic properties, including stable effective permeability (le) of 57.8 up to 1 MHz, excellent DC bias performance of 59.3 % at a bias field of 100 Oe, and the lowest Pcv of 194.7 mW/cm3 at a frequency (f) of 150 kHz and maximum magnetic induction (Bm) of 50 mT.(c) 2023 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.