C/C-(HfZrTi)C composites prepared by a novel precursor infiltration and pyrolysis method: A silicon-free strategy to improve the ablation resistance at ultra-high temperatures

To address the rapid volatilization and decomposition of SiO 2 at ultra-high temperatures, a silicon-free strategy has been proposed for the design of C/C-(HfZrTi)C composites. These composites were fabricated using a precursor infiltration and pyrolysis method that employed metal chloride and furfuryl alcohol as precursors. The resulting C/C-(HfZrTi)C composites demonstrated exceptional ablation resistance, with a mass ablation rate of −0.567 mg/s and a linear ablation rate of 1.433 μm/s when exposed to a 2.4 MW/m² oxyacetylene flame. This enhanced ablation resistance is attributed to the formation of liquid TiO 2 during the ablation process. The liquid TiO 2 can penetrate oxide scales through capillary action, forming an oxygen diffusion barrier that inhibits the oxidation of the composites. Additionally, it can bond with solid (HfZr)O 2 particles, resulting in the formation of a dense (HfZrTi)O 2 oxide scale that improves resistance to flame scouring. This work provides a new method and strategy for the preparation and design of silicon-free composites for ultra-high temperature applications.