Nature-inspired (Ti,Zr,Hf)C/SiC micro-nano composites with enhanced ablation resistance through a Gobi Desert-like protective oxide layer

(Ti,Zr,Hf)C/SiC composites with micro-nano structure were designed inspired by the gravel–sand structure of the wind-resistant Gobi Desert to prevent air-plasma flame scouring and obtain excellent ablation resistance. Dense (Ti,Zr,Hf)C/SiC micro-nano composites were synthesized via pyrolysis of Ti_0.2–Zr_0.3–Hf_0.5–vinylhydridopolycarbosilane (VHPCS) precursors with different contents of (Ti_0.33Zr_0.33Hf_0.34)C micropowders and sintered at 2200 °C. During heat treatment, the elemental diffusion between micropowders and polymer-derived ceramics leads to the formation of a single-phase (Ti_0.32Zr_0.32Hf_0.36)C solid solution with both micro- and nano-grains. Compared with the micro composites, micro-nano composites exhibit enhanced ablation resistance at approximately 2200 °C, with negative linear and mass ablation rates of −0.12 μm/s and −1.01 mg/s, respectively. This improvement results from the formation of a stable and dense protective oxide layer consisting of microscale (Ti,Zr,Hf)O₂ skeletons derived from (Ti_0.32Zr_0.32Hf_0.36)C_micro, uniformly dispersed (Ti,Zr,Hf)O₂ nanoparticles derived from (Ti_0.32Zr_0.32Hf_0.36)C_nano, and a SiO₂/(Zr,Hf)TiO₄ phase matrix. The refractory (Ti,Zr,Hf)O₂ microskeletons and nanoparticles collectively protect the molten matrix from air-plasma flame scouring, similar to the wind-resistant mechanism of the Gobi Desert, in which multisized gravel stabilizes the mobile sands.