Preparation and Microwave Absorption Properties of Double-Layer Hollow Reticulated SiC Foam

High-performance microwave absorption and being lightweight have become the foremost crucial factors in the practical application of mordern microwave adsorbers. In view of this, we presented the double-layer hollow reticulated SiC foam (DHRSF), which was planned to be used as a high-performance and lightweight microwave absorber. Reticulated carbon foam (RCF) obtained from the carbonization of melamine foam acted as the original reticulated template, where SiC, pyrolytic carbon (PyC), and SiC were sequentially deposited by chemical vapor deposition (CVD), chemical vapor infiltration (CVI), and CVD, respectively. DHRSF was then obtained by removing the carbon component during oxidation. The morphological results indicated that the special hollow and reticulated structures were fabricated successfully, which was considered to be the crucial factor for the microwave absorption. Numerous loose columnar SiC defects on the skeleton surfaces introduced a large number of trapping centers and interfaces to further improve the microwave absorption performances. The minimum reflection loss (RL) value of DHRSF could reach −41.39 dB at 7.2 GHz when the absorber thickness is 12 mm. It was also proven that all the minimum RL values are blow −20 dB at the thicknesses of 5–15 mm. Furthermore, the microwave absorption mechanism based on the special structures was discussed in detail, which provides a practical reference for the structure optimization of advanced microwave absorbers.