▎ 摘　　要

In this account, RGO-SiCnw/SiBCN composite ceramics were fabricated using polymer derived ceramic (PDC) combined with chemical vapor infiltration (CVI) technology. Dielectric property of as-obtained RGO-SiCnw/SiBCN composite ceramics was significantly enhanced thanks to established conductive pathway through overlapped nanoscale SiCnw and micro-sized RGO. The minimum RC of composite ceramics with 0.5 wt% GO and 2.29 wt% SiCnw at thickness of 3.6 mm reached -42.02 dB with corresponding effective absorption bandwidth (EAB) of 4.2 GHz. As temperature rose from 25 to 400 degrees C, permittivity increased with enhanced charge carrier density and then it decreased due to oxidation process of RGO from 400 to 600 degrees C. The minimum reflection coefficient (RC) was recorded as -39.13 dB and EAB covered the entire X-band at 600 degrees C. EMW absorption ability was evaluated after high-temperature oxidation experiment under protective effect of wavetransparent Si3N4 coating. RGO-SiCnw/SiBCN composite ceramics maintained outstanding EMW absorption ability with minimum RC of -10.41 dB after oxidation at 900 degrees C, indicating RGO-SiCnw/SiBCN composite ceramics with excellent EMW absorption characteristic even at high temperatures and harsh environments.