Needle-punched preform orientation governs cyclic ablation resistance of C/C–HfC–SiC composite leading edges

Ultra-high-temperature ceramic-modified 2.5D needle-punched carbon/carbon (C/C) composites, known for their high-temperature strength and ablation resistance, are promising candidates for the sharp leading edges (SLEs) of advanced aircraft. However, the needle-punched architecture and the associated ceramic networks introduce anisotropy in thermal and oxidation responses. Here, three C/C–HfC–SiC SLEs with distinct preform orientations were fabricated via precursor infiltration and pyrolysis to investigate how the matching between preform orientation and heat flux governs heat transfer, oxidation, and failure modes. The best-aligned configuration exhibited outstanding cyclic ablation resistance, retaining its sharp geometry after five ablation cycles (600 s in total, ∼2700 °C) with a linear recession rate of only 0.03 µm s⁻¹. Thermal-transport analysis revealed its highly efficient heat dissipation, which alleviated tip overheating. The extensive ceramic coverage on its windward surface, together with the continuous oxide scales connected by needle-introduced ceramics, forms a protective ceramic network that preserves the structural integrity of the SLE. These results identify orientation–heat-flux matching as a key factor for durable ablation protection and improved reliability of C/C-based SLEs.