Synergistic enhancement of radar wave absorption in SiC/Al₂O₃ composites via structural tuning, composition optimization, and unit design

Due to the limitations in structure and loss mechanisms, achieving both excellent reflection loss and broadband electromagnetic absorption simultaneously has been challenging for SiC-based materials. In this study, an innovative approach was adopted to fabricate Al₂O₃-modified SiC (SiC/Al₂O₃) ceramic matrix composites by polymer impregnation and pyrolysis method, and oxidation of a carbon framework. Through structural engineering, the introduction of Al₂O₃ phase established different loss mechanisms, such as dielectric loss and conductive loss. During the X-band (8.20–12.40 GHz), the resulting composite achieved a minimum reflection loss (RL_min) of −50.52 dB at a thickness of 2.20 mm, with an effective absorption bandwidth (EAB) of just 2.28 GHz. Building upon this foundation, two different periodic metamaterial structures were designed to optimize the electromagnetic absorption performance of the SiC/Al₂O₃ composite. By employing a multi-scale design strategy, significant improvements in both RL_min and EAB were achieved innovatively. The cross-shaped structure achieved efficient absorption across a frequency range of 8.20–12.40 GHz, reaching an RL_min of −78.69 dB and an EAB of 3.32 GHz at a total thickness of 2.80 mm. This research provides a novel approach for designing advanced SiC-based metamaterials with excellent radar stealth performance in the X-band.