Optimizing the electromagnetic wave absorption bandwidth of SiC/C aerogels using continuous multi-band absorption

Designing electromagnetic wave (EMW) absorbers with continuous multi-band absorption is essential for enhancing their effective absorption bandwidth (EAB). However, achieving such absorption through microstructural design remains challenging. In this study, CNTs were firmly and uniformly attached to the surface of cellulose microsheets by a self-assembly process. After carbothermal reduction, the CNTs were transformed into SiC nanorods, and the cellulose microsheets were converted into SiC/C microsheets, yielding novel SiC/C aerogels with gradient variations. The SN-1450 sample demonstrated continuous triple-peak EMW absorption with a maximum EAB of 11.04 GHz. Three absorption peaks appeared in the C-, X-, and Ku-bands, respectively, covering the full X- and Ku-bands and nearly half of the C-band. A comparative analysis of the EMW absorption performance after high-temperature oxidation revealed that the C-band peak originated from the carbon component, while the X- and Ku-band peaks were attributed to SiC. The carbon in SN-1450 increased conductivity, and contributed to the improvement of conductivity and polarization losses of the EMW absorption in the C-band. This study provides valuable insights into continuous multi-band EMW absorption and offers a framework for using microstructural design to enhance the EAB of SiC-based porous materials.