Synergistic enhancement of structure and function in carbonaceous SiC aerogels for improved microwave absorption

As space science and technology rapidly advance, spacecraft are increasingly subjected to severe thermal and electromagnetic environments. This has created an urgent demand for materials that offer both microwave absorption and thermal insulation. Herein, we present one-dimensional (1D) carbon nanotube (CNT)/SiC nanostructure-reinforced SiC-based aerogels via carbothermal reduction of resorcinol-formaldehyde/silica composite aerogels containing CNTs. These composite aerogels were presynthesized using a straightforward one-pot sol-gel method, subsequently undergoing supercritical CO₂ drying. Conduction loss and mechanical strength are both simultaneously improved by the in-situ formation of 1D CNT@SiC core-shell nanostructures within granular SiC aerogels. The optimized SiC-based aerogel demonstrates exceptional performance, achieving a minimum reflection loss of −66.01 dB and the effective absorption bandwidth reaching 6.76 GHz. Additionally, it maintains a thermal conductivity of 0.0582 W/(m·K) at 25 °C, alongside a Young's modulus of 45.2 MPa at a density of 0.242 g/cm³. This design seamlessly combines various functionalities within the SiC-based aerogel system, offering significant guidance towards the development of cutting-edge functional aerogels designed to withstand extreme environmental challenges.