Thermal-insulation and ablation-resistance of Ti-Si binary modified carbon/phenolic nanocomposites for high-temperature thermal protection

•Novel Ti-Si binary modified carbon fiber reinforced phenolic aerogel nanocomposites was originally designed.•Cf/PR-TS has good thermal insulation and thermal stability in addition to maintaining mechanical strength and low density.•Outstanding ablation resistance in different ablative environments.•Ablative insulation mechanisms of surface ceramicization reverse radiation and SiO2 fusion-clad oxygen barrier. Ablative thermal protection systems are considered to be one of the most promising means of protection for spacecraft re-entry, but challenges remain. Herein, efficient Ti-Si binary modified carbon fiber reinforced phenolic aerogel nanocomposites (Cf/TS-PR) were originally designed based on a multi-stage construction strategy. The Cf/TS-PR exhibited desirable mechanical strength, good thermal insulation with a minimum thermal conductivity of 0.0756 W/(m·K), remarkable thermal stability and outstanding ablation resistance, benefiting from the features of TiO2 and the special structure of TiO2-SiO2 coating. The linear ablation rates are as low as 0.004 and 0.003 mm/s at the heat flow of 1.0 and 1.5 MW/m2, respectively. The mass loss rates are as low as 0.006 and 0.009 g/s at the heat flow of 1.0 and 1.5 MW/m2, respectively. These results indicate that the Cf/TS-PR nanocomposites can be a reliable thermal protection material for the future high-temperature service environment of ultra-high-speed vehicles and neutral rockets.