Epoxy resin addition on the microstructure, thermal stability and microwave absorption properties of core-shell carbonyl iron@epoxy composites

Highlights: • Carbonyl iron@epoxy microspheres are prepared by in-situ polymerization. • The mechanism relies on multiple scattering and impedance matching. • The oxidation resistance and acid-base stability of carbonyl iron powder have been improved to a great extent. -- Abstract: In this study, novel CIP@EP composites with a core-shell structure were prepared by using the in-situ polymerization method. The phase structure, morphology and thermal stability were investigated by FTIR, XRD, SEM, TEM and TG. The results indicated that EP were densely covered on the surface of CIP particles, and with the increase of EP contents, the EP shell became thicker, which effectively strengthened the thermal stability of the materials. The magnetic and electromagnetic properties of the composites were systematically investigated. It was found that the content of EP played an important role in improving the magnetic and dielectric properties. High EP content can effectively improve the impedance matching between the dielectric and magnetic loss of the absorbers and enhance the EM wave absorption ability of the composites. This study proves that the CIP@30%EP exhibits an excellent EM wave absorption ability, which has higher value of R_L and wider absorption width than other CIP@EP composites. The CIP@30%EP has a strong reflection loss peak of −16.1 dB and wide effective absorption bandwidths of 5.4 GHz at the thickness of 2.2 mm. Furthermore, the method utilized to synthesis the CIP@EP composites can be a suitable and efficient way to prepare other spherical microwave absorption materials.