Morphology and Magnetic Properties of Carbonyl Iron‐Based Soft Magnetic Composites With the Coating of Silicone Modified Epoxy Resin

ABSTRACT Organic resin has been considered as a crucial component for the preparation of high‐performance soft magnetic composites (SMCs). To combine the advantages of epoxy resin and silicone resin, a silicone chemically modified epoxy resin (SME) was synthesized for carbonyl iron‐based SMCs through the condensation reaction between the terminated methoxy groups of methyl phenyl silicone intermediate and the hydroxyl groups of bisphenol‐A type epoxy resin. The chemical structure of SME was characterized, and the effects of the amount of modified resin on the microstructure, mechanical properties and magnetic properties of SMCs were studied. As the amount of SME resin increased, the resistivity of the SMCs gradually increased, the eddy current loss, core loss and effective permeability gradually decreased, and the crushing strength first increased and then decreased. When the amount of SME resin was 3 wt%, the SMC exhibited the best comprehensive properties, and the eddy current loss and core loss were only 0.99 and 434.2 mW cm −3 at 50 mT/100 kHz, respectively. Meanwhile, the resistivity, effective permeability and crushing strength respectively reached 2.36 TΩ cm, 23.4 and 11.95 kgf, which were obviously superior to those of the SMCs prepared with epoxy resin and silicone/epoxy mixed resin.