Synthesis and characterization of carbonyl iron@epoxy core–shell microspheres for enhanced microwave absorption performance

Abstract

Carbonyl iron powder (CIP) coated with a layer of epoxy (EP) shell, denoted as core–shell CIP@EP composites, were designed and prepared via in situ polymerization. The CIP@EP composites containing 4.5–6.8 wt% EP were systematically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometer, scanning and transmission electron microscopy, and vector network analyzer. The results indicated that CIP@EP composites with 9–254 nm EP shell thickness were successfully prepared through an efficient in situ polymerization method. The particle diameter of core CIP particles was 0.49–4.24 µm. The microwave absorption properties of the microspheres were then experimentally measured, and the CIP@EP composites exhibited a maximum reflection loss value of − 66.2 dB at 7.1 GHz at 2.0 mm absorber thickness. The effective absorbing bandwidth below − 10 dB was 8.0 GHz (from 10.0 to 18.0 GHz). The presence of the EP shell not only enhanced the microwave absorption performance of CIP@EP composites but also improved the overall chemical stability of CIP particles. The as-prepared CIP@EP composites may be a promising candidate for electromagnetic wave absorption applications, and the core–shell structure design can be extended to other microwave absorption materials.