Study on the magnetic property of Fe-Si-B amorphous magnetic powder core coated with Al2O3/phosphoric acid-Al2O3 double layer

To study the magnetic loss of electronic devices in high-frequency applications, Fe-Si-B magnetic powder cores coated with Al2O3 or phosphoric acid-alumina composite coating were prepared. In this paper, the effects of nano-Al2O3 powders and phosphoric acid with different contents on magnetic properties such as magnetic loss and permeability of magnetic materials were investigated. In addition, three kinds of amorphous Fe-Si-B powders (D-50=21.78 mu m, 11.59 mu m, 5.554 mu m) were mixed to find the best particle size ratio. The results show that the coating of mixture of 0.8 wt% phosphoric acid and 0.2 wt% Al2O3 achieves excellent magnetic properties (mu '=22.34; P-cv=205.4 mW/cm(3) measured at 1000 kHz, 20 mT) with a particle size ratio of 2:6:2.