Preparation for High-Frequency Soft Magnetic Composites with Carbonyl FeNi50

Carbonyl soft magnetic composites (SMCs) have garnered significant attention due to their excellent high-frequency adaptability and outstanding properties, aligning perfectly with the development trend of electronic components. In this work, carbonyl FeNi50 powders were chosen as the research subject, and phosphating treatment was utilized to generate a phosphate coating layer on the surface of the powders. The influences of phosphoric acid concentrations on the compositions and structures of the phosphate coating layer on the powders’ surface were systematically investigated by combining various characterization techniques. The presence of phosphates was successfully characterized, and the reactions between phosphoric acid and the FeNi50 powder were inferred. Subsequently, the magnetic properties of the SMCs were measured, and the influences of phosphoric acid concentrations on the magnetic properties of the SMCs were investigated. The comprehensive magnetic properties of SMCs were found to be optimal at a phosphoric acid concentration of 0.15 wt%. In particular, the DC bias performance of up to 91.0% and the permeability stability of up to 20 MHz could meet the requirements of high-frequency and large DC bias applications, indicating extensive application prospects.