Developing multifunctional lightweight thermal protection materials with reliable insulation, ablation resistance, and wave transparency is crucial for advanced thermal protection systems. Herein, SiOC aerogel-based composites were fabricated via a scalable polymer-derived route using organosilane aerogel precursors, which exhibit low densities of 0.35–0.65 g·cm–3, ultralow thermal conductivities of 0.046–0.058 W·m–1·K–1, and superior wave transparency with a transmittance >80% at 8–18 GHz. Such exceptional performance stems from the high-fidelity preservation of a nanoporous, low-carbon SiOC network during the polymer-to-ceramic transition. Under oxy-acetylene ablation at 1200–1600 °C, the SiOC composites demonstrated a 20–60% reduction in mass loss and 15–45% lower linear recession relative to polymeric precursors, attributed to the formation of a continuous, SiO2-rich passivating layer. Furthermore, the influence of four representative fibers on the dielectric and ablation properties was investigated, revealing a strong dependence on the fiber chemistry. The degradation pathways are categorized into surface densification or fiber oxidation- and melt-softening-dominated processes. This study elucidates the mechanisms of dielectric and thermochemical evolution from both nanoporous matrix and fiber perspectives, providing a reference for the design of multifunctional thermal protection materials.
Tian et al. (Tue,) studied this question.