Polysiloxane encapsulating strategy to enhance the high-temperature electromagnetic wave absorption performance of carbon-rich SiOC ceramics

Carbon-enriched polysiloxane-derived SiOC (C-SiOC) ceramics are promising electromagnetic wave absorption (EMA) materials. However, oxidation and impedance mismatch severely deteriorate their EMA performance at high temperatures. In this study, we used polysiloxane (PSO) to encapsulate the crosslinked precursor of C-SiOC ceramics. After pyrolysis, PSO-derived SiOC-encapsulated C-SiOC (here named PSO-C-SiOC) ceramics were obtained. The PSO-C-SiOC ceramics exhibit an improved oxidation resistance compared with C-SiOC ceramics and basically retain their original dielectric and EMA properties after exposure to air at high temperatures. Moreover, the ceramics can maintain excellent EMA properties at elevated temperatures with good impedance matching. The remarkable high-temperature EMA properties of PSO-C-SiOC ceramics in air are attributed to the protective outer-layer of PSO-derived SiOC ceramic, which enhances oxidation resistance and simultaneously controls the impedance matching. These findings underscore the potential of PSO-C-SiOC ceramics as high-temperature EMA materials.