Abstract: High-performance thermal protection materials (TPMs) for spacecraft are becoming current research hotspots. Lightweight polymer-based ablators are considered to be the most promising candidates for TPMs due to their excellent designability and versatility. In this study, a unique nano-TiO₂ coated needled carbon fiber felt/phenolic resin aerogel composite (TiCF/PR) is reported. Wherein the anatase nano-TiO₂ was in-situ coated on the surface of carbon fibers uniformly through the sol-gel and calcination method, then, the phenolic resin aerogel was in-situ synthesized in the nano-TiO₂ coated needled carbon fiber felt (TiCF) preform through vacuum impregnation and solvothermal method. The as-prepared aerogel composite possesses a low density (0.30-0.32 g/cm³), low thermal conductivity (0.034 and 0.312 W/(m K) in the z and xy directions), and excellent thermal stability with 13.86% residual weight at 1300 °C in air. It is worthwhile to note that the TiCF/PR composite exhibits excellent antioxidant ablation and infrared (IR) radiation shielding properties in a high-temperature heating environment. With an oxygen-acetylene blaze heating of 1.5 MW/m² for 150 s, the linear ablation rates decreased by 13.4%, and the backside temperature reduced from 322.3 to 179.1 °C compared to that of the sample without nano-TiO₂ coating. The experimental and theoretical analysis showed that the present TiCF/PR nanocomposite has competitive and potential application prospects in the field of future TPMs.

Key words: Carbon fiber, Opacifier, Mechanical properties, Thermal properties, Ablation performance