Cyclic ablation behavior of gradient C/C-Hf0.5Zr0.5C composites exposed to an oxyacetylene torch at a heat flux of 4.18 MW/m2

Gradient C/C-Hf0.5Zr0.5C 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 mu m/s after being ablated for 30 s x 3.