Novel preparation of FeCo alloy/graphene foam composites for efficient microwave absorption

Abstract

Five groups of FeCo alloy/graphene foam (FeCo/GF) composites with different GF contents (1%, 2%, 3%, 4%, and 5% of the mass of the FeCo alloy) were prepared in this work. The results show that the morphology, saturation magnetization, and electromagnetic parameters of the composites were greatly affected by the GF amount. The reticular porous structure of GF significantly increases the multiple scattering events and loss paths of electromagnetic waves and provides an excellent electric loss. Being a typical soft magnetic material, FeCo exhibits a high saturation magnetization and an excellent magnetic loss. The FeCo/GF composite has excellent microwave absorption properties, which are attributed to its superior dielectric loss, conductive loss, natural resonance, and exchange resonance loss mechanisms. In particular, when the content of GF is 3% of the mass of FeCo alloy, it exhibits the best effective absorption bandwidth. With a matching thickness of only 1.85 mm, this composite achieves a maximum effective absorption bandwidth of 7.2 GHz (10.8–18 GHz). Additionally, when the content of GF is 4% of the mass of FeCo alloy, the sample exhibits the lowest reflection loss, which reaches −61.68 dB at a frequency of 3.44 GHz.