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

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.