Structure and magnetic properties of FeSiAl-based composites with the compound passivation agent

FeSiAl soft magnetic composites (SMCs), which are widely used in electromagnetic applications, have good electromagnetic characteristics. To reduce their core loss, the current research focuses on improving the properties of insulating coating materials. In this work, different contents of phosphoric acid and chromic acid compound passivating agents are used to prepare the insulation coating of FeSiAl powder. The results revealed that the surface film layer of the powder coating with the compound passivation agent is relatively smooth, and the film layer is too thin to be detected by XRD. With the increase of the amount of passivating agent, the permeability of powder decreases gradually and the performance of anti-DC-Bias loading improved. The core loss shows a trend that it decreases first and then increases with the increase of passivating agent dosage. If the amount of passivator is too much, the core loss will increase rapidly. When a 2% passivator is used, the magnetic permeability of the powder is 72, the DC-Bias characteristic is 51.3% with 100 Oe, and the core loss is 57 mW cm−3 at 100 kHz and 50 mT.