SiO2-Al2O3 aerogel networks reinforced C/CA composites for synergistically enhanced electromagnetic interference shielding and thermal protection

An in situ SiO 2 -Al 2 O 3 aerogel network repairs macropores and weak interfaces in C/CA. • Hierarchical interfacial reinforcement enhances mechanical strength, cyclic resilience, and electromagnetic shielding. • The composite provides efficient thermal insulation and stable protection under high heat-flux and repeated flame ablation. Carbon aerogels and their fiber-reinforced composites (C/CA) show great promise for thermal protection owing to their lightweight, porous structure and excellent thermal stability. However, their susceptibility to high-temperature oxidation and macroscopic defects induced by shrinkage mismatch during carbonization severely limit reliable service in extreme environments. To address these challenges, this work proposes a carbon/ceramic aerogel composite design strategy based on the synergy between heterogeneous interface reinforcement and in situ defect repair. A continuous SiO 2 -Al 2 O 3 aerogel network was in situ constructed on the surface and within the pores of the C/CA skeleton via a sol-gel method, yielding lightweight C/CA-SiO 2 -Al 2 O 3 composites with high strength, durable thermal protection, and electromagnetic interference shielding capability. The optimized C/CA-SiO 2 -Al 2 O 3 -3 exhibited high specific surface area and excellent mechanical properties, maintaining stable stress-strain responses after 100 compression cycles. Benefiting from synergistic effects of conduction loss, interfacial/dipole polarization, and multiple scattering, its total electromagnetic interference shielding effectiveness was enhanced by approximately threefold. Moreover, the composite showed outstanding ablation resistance, retaining low back-side temperature and good shape integrity after five repeated ablation cycles. This work provides a carbon/ceramic aerogel composite design strategy integrating heterogeneous interface reinforcement, functional limitations of large-area thermal protection materials under repeated high-temperature exposure and repeated service. Download: Download high-res image (449KB) Download: Download full-size image