Cyclic ablation behavior of gradient C/C-Hf_0.5Zr_0.5C composites exposed to an oxyacetylene torch at a heat flux of 4.18 MW/m²

Gradient C/C-Hf_0.5Zr_0.5C composites (CHZC) were synthesized via chemical liquid vapor deposition technology (CLVD). The composition, microstructure, and cyclic ablation behavior were investigated under an oxyacetylene flame with a heat flux of 4.18 MW/m². The results manifest that the ceramic content exhibits a gradient distribution in the axial direction, increasing from the center toward the edge. Throughout the ablation process, defects and voids are healed by highly fluid molten ZrO₂ that effectively prevents oxygen infiltration, and the molten ZrO₂ is pinned by HfO₂ particles, allowing the molten layer to resist better high-temperature erosion. Besides, the gradient structure effectively suppresses the initiation of cracks in the substrate. Consequently, CHZC demonstrates superior anti-ablation performance, with the mass recession rate (MRR) of −0.12 mg/s and linear recession rate (LRR) of −0.22 μm/s after being ablated for 30 s × 3.