Synthesis and tunable electromagnetic shielding and absorption performance of the three-dimensional SiC nanowires/carbon fiber composites

Silicon-carbide nanowires (SiCnws) have been considered as dielectric loss materials for application in the field of electromagnetic wave (EMW) attenuation. In this study, SiCnws/carbon fiber (CF) composites were fabricated using precursor infiltration and pyrolysis process for the in-situ growth of SiCnws. The SiCnw fraction of the SiCnws/CF composites could be adjusted using various catalysts. At a small SiCnw fraction (38 wt%), the composites exhibited excellent EMW absorption performance with the minimum reflection loss of - 18.3 dB when their thickness was only 1.2 mm and can cover the entire X and Ku bands by adjusting the material thickness. They transformed from EMW absorption performance to electromagnetic interference (EMI) shielding property with the increase in SiCnw fraction from 38 wt% to 73 wt%, reaching an EMI shielding effectiveness of 31.25 dB. In addition, the density of the SiCnws/CF composites was only 0.31-0.41 g/cm3, and their compressive strength can reach 0.61-0.99 MPa with excellent high-temperature stability. Therefore, the SiCnws/CF composite presents a promising EMW absorption and EMI shielding material that can be applied in harsh environments.