Effect of HfC nanowire diameter on the ablation resistance of C/C-HfC-SiC composites

Hafnium carbide (HfC) nanomaterials hold significant potential for enhancing the performance of ultra-high temperature ceramic matrix composites. However, achieving the synergistic optimization of their mechanical and ablation resistance properties through controllable synthesis remains a challenge. To address this issue, this study employed a nickel-catalyzed pyrolysis method using hafnium tetrachloride (HfCl 4 ) and furfuryl alcohol as precursors. By precisely controlling the catalyst concentration within a carbon/carbon (C/C) preform, the controlled synthesis of HfC nanowires (HfC NWs ) with two distinct diameters (500 nm and 1000 nm) was successfully achieved. Subsequently, corresponding C/C-HfC-SiC composites (denoted as HS-1 and HS-2) were fabricated via the polymer impregnation and pyrolysis (PIP) process. The results demonstrate that the HS-1 composite modified with 500 nm HfC NWs exhibits the most superior performance: its flexural strength was significantly increased by 51.84 % compared to the unmodified sample, and it displayed the best ablation resistance after 60 s of exposure to an oxyacetylene flame. In-depth characterization revealed that this enhancement originates from the dense three-dimensional network formed by the finer nanowires, which effectively traps ceramic particles and facilitates the formation of a denser, more protective oxide layer. This work elucidates the critical role of nanowire diameter control and provides valuable insights for designing high-performance composites for extreme environments.