Effect of AlN coating on the electromagnetic properties of FeSiAl soft magnetic composites

Abstract Soft magnetic composites (SMCs) are considered key elements for attaining electromagnetic signal transmission and conversion. However, they require high permeability and low core losses to ensure the efficient and stable operation of electronic devices, such as inductors and sensors. To effectively address these issues, in this work, AlN nanopowders were used to coat FeSiAl spherical particles. In parallel, the effect of coating AlN nanopowders on the electromagnetic properties of FeSiAl SMCs was investigated. By performing energy dispersive spectroscopy analysis, AlN was confirmed to be attached to the FeSiAl spherical particles, indicating the existence of an excellent AlN coating quality. Although the incorporation of the AlN coating layer yielded a monotonic reduction in saturation magnetization intensity and effective permeability, it also effectively suppressed core losses. Due to the high-resistance of AlN, the high-resistance layer developed on the surface of the FeSiAl particles can substantially increase the resistivity of FeSiAl SMCs, and then the eddy current loss was suppressed. When coated with 1.5 wt% AlN, the FeSiAl SMCs exhibited the lowest core losses of 394 kW m −3 at 100 kHz, 100 mT, and room temperature. The proposed AlN-coated FeSiAl SMCs in this work exhibited a good overall performance, and are expected to be applied in high-performance inductor devices.