Impact of the exfoliated graphite on magnetic and microwave properties of the hexaferrite-based composites

Abstract

RAM (Radar absorbing materials) is strategically important to prevent the targets from being identified. A necessary condition for the absorption of most of the incoming radiation, depending on a combination of conductivity, permittivity, and permeability of the composite's different components, is wave impedances balanced at an air/shield interface. The paper presents a novel RAM developed with the use of exfoliated graphite (EG) for the preparation of composite samples in polyvinyl fluoride (PVDF) in the presence of magnetic inclusion of hexaferrite (HF). The prepared samples were characterized by X-ray diffraction (XRD) and Raman spectroscopy. The morphology was studied by using scanning electron microscopy (SEM). The magnetic properties of all the samples were analyzed by using a vibrating sample magnetometer (VSM). The composites were tested for RAM properties using a vector network analyzer (VNA) in the range of 0.7–7 GHz. The study shows the optimum weight percentage of HF, PVDF, and EG for obtaining high RAM. Inside the prepared composites, EG acts as a conductive path, increasing dielectric and magnetic losses, both of which are critical for trapping incoming electromagnetic radiations and improving total electromagnetic shielding by absorption. In maintaining conductive trajectories in electromagnetic radiation absorption, EG has a significant role in raising the overall shielding efficiency (performance) by more than 50 dB, indicating that the prepared composites in this study can absorb 99.9% of the incoming electromagnetic radiation. The studied composites can be promising absorption blocks in electromagnetic interference (EMI) shielding applications.