Enhanced heat-resistance property of aluminum-coated carbonyl iron particles as microwave absorption materials

Abstract Nano aluminum (Al)-coated carbonyl iron particles (CIPs) with high microwave absorption capacity and heat-resistance property were prepared by ball-milling. To test the performance of Al@CIPs, raw CIPs were also processed under the same ball-milling process for comparison. Afterwards, both materials were subjected to the same heat treatment process in order to examine their heat resistance. The morphology, structure, electromagnetic and microwave absorption properties were evaluated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and vector network analysis, respectively. The bond properties of CIPs- or Al@CIPs-based coatings were determined through pull-out test. Morphological and structural analysis results indicated that Al nanoparticles were homogeneously distributed on the surface of CIPs. Compared with raw CIPs, Al@CIPs composites had the better oxidation resistance. The significant improvement in the antioxidation capacity was mainly attributed to the compact and dense alumina layer formed at the higher temperature, which further prevented oxygen in the air from entering the CIPs core. The ball-milling method proposed in the study can uniformly coat Al on the surface of CIPs in a simple and effective way and provide an efficient way to prepare antioxidized CIPs as microwave absorption materials.