Ceramizable and mechanically robust aramid nanofiber/phenolic aerogel composites via Zr-Si interface engineering for thermal protection

Thermal protection materials (TPMs) serve as a critical barrier ensuring the safe flight of spacecraft. Achieving simultaneous optimization of load-bearing capacity and ablation resistance in TPMs while maintaining lightweight characteristics poses a significant challenge. To address this, the present study proposes an interface engineering strategy that constructs an interface-ceramizable aramid nanofiber (ANF) preform reinforced phenolic aerogel composites. The ANF not only provides essential mechanical support but also endows the material with structural stability under high-temperature ablative environments. Benefiting from the design of the interface layer, the ANF and phenolic aerogel are tightly bonded; during the pyrolysis process, their linear shrinkage rates are highly compatible, effectively suppressing the formation of microcracks. Meanwhile, the surface functional layer can be in-situ sintered into high-temperature-stable phases (e.g., SiC, ZrC), significantly improving ablation resistance. The resulting composites exhibit a density as low as 0.327 g/cm 3 and a compressive modulus as high as 285.7 MPa, allowing flexible adaptation to various application requirements. Notably, after exposure to a butane flame for 120 s, the linear and mass ablation rates reach 0.0113 mm/s and 0.00134 g/s, respectively, with the back temperature only 100.9 °C. This strategy offers a fundamental solution and a scalable fabrication route for next-generation high-performance thermal protection systems for spacecraft.