Abstract: Developing lightweight electromagnetic wave (EMW) absorbers with excellent high-temperature stability is highly desirable for aerospace and extreme-environment applications. Herein, a SiC@C aerogel (SCA) with a hierarchical porous structure and a nanowire-microfiber multiscale conductive network was fabricated via an in-situ carbothermal reduction strategy. The hierarchical porous architecture promoted EMW multiple scattering, while the interconnected conductive network and abundant SiC@SiO₂ heterogeneous interfaces enhanced conduction and polarization losses. The optimized SCA achieved excellent microwave absorption performance, with a minimum reflection loss (RL_min) of -45.9 dB and a maximum effective absorption bandwidth (EAB_max) of 3.2 GHz. After oxidation at 800 ℃, SCA still exhibited an RL_min of -30.6 dB and an EAB_max of 2.72 GHz, which indicates that SCA has strong high-temperature stability in EMW absorption performance. DFT calculations revealed that the formation of a SiC@SiO₂ heterointerface promoted interfacial electron transfer and polarization, thereby enhancing dielectric loss. Furthermore, SCA has a density of only 0.11 g cm^-3, and also exhibits excellent thermal stability and insulation properties. This work provides a novel strategy for designing and developing next-generation multifunctional electromagnetic wave absorbing materials that combine efficient wave absorption with extreme thermal stability.

Key words: Electromagnetic wave absorption, Heterointerface, SiC nanowires aerogel, Thermal stability, Multifunctional