Strong and thermostable SiC nanowires/graphene aerogel with enhanced hydrophobicity and electromagnetic wave absorption property

Abstract SiC nanowires (SiCnws) were incorporated in supercritical-ethanol-dried graphene aerogel (GA–S) via chemical vapor infiltration (CVI) to fabricate a lightweight, thermostable, high-performance electromagnetic (EM) absorbing composite. The SiCnws improved the yield strength of GA–S from 0.15 MPa to 0.47 MPa in the linear elastic region. The oxidation temperature of GA–S contained in situ grown SiCnw exceeded 660 °C in air. The double-scale surface roughness increases the water contact angle from 53° of GA–S to 134° of SiCnw/GA–S. The SiCnw/GA–S composite showed a minimum EM wave reflection loss (RL) value of −54.8 dB at 5.3 GHz with thickness of 3.63 mm. The SiCnw/GA–S sample demonstrated a wide effective absorbing bandwidth of 6.5 GHz from 9.3 to 15.8 GHz at thickness of 2.0 mm. In addition, the SiCnw/GA–S sample could achieve effective absorption covering the entire X-band in a wide thickness range of 2.2–2.7 mm. Three-dimensional networks and residual oxygen functional groups of GA–S, the high-density stacking faults, and the abundant interfaces between SiCnws and graphene sheets played important roles in enhancing the EM dissipation of SiCnw/GA–S composites. The SiCnw/GA–S composites are promising EM-wave-absorbing materials in extreme environment.