Selection of insulation coatings for industrial-grade FeSiBC amorphous soft magnetic composites based on dry particle coating method

Compared with wet coating, dry particle coating is an efficient, low-cost and pollution-free method. In this study, FeSiBC@Fe₃O₄, FeSiBC@SiO₂ and FeSiBC@MgO soft magnetic composites (SMCs) were prepared based on dry particle coating, and FeSiBC@Phosphate was also prepared by passivation method. The performance of different insulating coatings was compared through performance characterization and loss separation calculation, and then the applicability of the dry particle coating method to the flake powder was analyzed. The results show that, for the flake powder produced by pulverization of amorphous ribbons, the coating uniformity prepared by passivation method is poor, resulting in high core loss and low permeability of FeSiBC@phosphate. The MgO coating is poorly bonded with the powder, resulting in poor magnetic performance of FeSiBC@MgO. Although the total loss can be significantly reduced by the SiO₂ coating, the permeability is also reduced to 26.7 due to the severe magnetic dilution effect. Fe₃O₄ with subferromagnetic properties not only possesses excellent insulating properties, but also improves the local ferromagnetic exchange coupling, and the corresponding FeSiBC@Fe₃O₄ exhibits optimal soft magnetic properties, with the permeability of 36.2 and the core loss of 5.58 J·m⁻³ (0.05 T and 200 kHz). The prepared FeSiBC@Fe₃O₄ exhibits excellent performance, and its preparation path based on the dry particle coating is cost-effective, featuring excellent industrial compatibility and broad application prospects.