Enhanced soft magnetic properties of the Fe-based amorphous powder cores with novel TiO2 insulation coating layer

The core-shell structured FeSiBCCr@TiO₂ amorphous magnetic powder cores (AMPCs) with excellent comprehensive magnetic properties were successfully prepared using spherical amorphous powders with high quality insulating layer. Scanning electron microscopy, Energy dispersive X-ray spectroscopy analysis, X-ray diffraction, and Fourier transform infrared spectroscopy revealed that the surface of the Fe-based amorphous powders was covered by a continuous amorphous TiO₂ insulation layer. The performances of the AMPCs can be well tuned by changing the thickness of the insulation coating layer, which can be adjusted by controlling the concentration of tetrabutyl titanate (TBOT) in the hydrolysis and condensation reaction system. After annealing at 480 °C for 1 h, the AMPCs with TBOT concentrations of 0.15 ml/g exhibited excellent comprehensive soft magnetic properties, including the highest quality factor of 104.5 at 560 kHz and lowest core loss of 265 mW/cm³ at f = 100 kHz and B_m = 0.05 T. It also maintained a relatively high permeability of 67 up to 5 MHz and superior DC-bias permeability of 68% at a bias field of 100 Oe. This study demonstrated a modified method to develop a novel insulation coating layer to reduce the core loss and improve the magnetic properties of AMPCs.