Simple and facile fabrication of lightweight, strong, thermal insulating ceramifiable aerogel‐like polysiloxane impregnated carbon/carbon composite with high antioxidant ablation performance

Abstract Lightweight ablative thermal protection materials (TPMs) with excellent ablation, thermal insulation, and anti‐oxidation are urgently needed for aerospace vehicles. Herein, a distinct strategy was proposed that uses aerogel‐like polysiloxane (SiA) as a matrix, and carbon‐bonded carbon fiber (C/C) composite as reinforcement to construct a lightweight SiA impregnated C/C (C/C‐SiA) composite, through vacuum impregnation, sol–gel, and atmospheric pressure drying. The intriguing characteristics including high mechanical strength and stiffness, thermal stability and oxidation resistance, and a low thermal conductivity of 0.063 W/(mK) were integrated into the low‐density (0.238–0.306 g/cm 3 ) C/C‐SiA. The synergistic effect originated from pyrolysis products of SiA including silicon oxycarbide ceramic to inhibit oxygen diffusion and pyrolysis gas to retard convective heat transfer, the high emissivity surface re‐radiation to dissipate heat and transverse thermal conductivity to regulate heat transfer by C/C, enables C/C‐SiA to deliver remarkable thermal insulation performance (20 mm backside temperature below 40°C on a heating plate for 1800 sec) and ablation resistance (near‐zero surface recession of 0.18 μm/s exposed to 1300°C flame for 1200 sec). The ceramifiable strategy can be extended to other preceramic polymers, such as polycarbosilane, polysilazane, and ZrO 2 precursor, which may open a new avenue for improving lightweight ablative TPMs. Highlights Aerogel‐like polysiloxane lightweight ablative material was fabricated. The synergistic effect gives excellent mechanical and thermal properties. Surface re‐radiation and heat blockage dissipate the main heat continuously. In‐situ formed ceramic to inhibit diffusion enables long‐term anti‐oxidation.