High permeability and low magnetic loss of Fe–Si/BN soft magnetic composites with layered structure

Abstract

Achieving low magnetic loss and high permeability remains a challenge for Fe–Si soft magnetic composites (SMCs). In this work, anisotropic Fe–Si/BN SMCs were prepared with the flaky Fe–Si/BN powders. Effects of BN content on the structure and electromagnetic properties of the Fe–Si/BN SMCs were studied. When the BN content increased, the surfaces of the flaky Fe–Si powders were gradually completely covered by BN nanosheets, a uniform BN coating formed and thickened. Owing to the low demagnetization factor of the flaky Fe–Si powders in the in-plane direction, demagnetization effect was effectively reduced. In addition, dynamic loss was significantly reduced by the increased BN content due to the good insulation of the BN coating. When the BN content was 6 wt%, the Fe–Si/BN SMCs exhibited low magnetic loss (71.76 W/kg at 0.05 T/50 kHz) and high permeability (127) with good frequency stability from 100 Hz to 100 kHz.