Fabrication and oxy-acetylene ablation behavior of Cf/TaC composites from an unsaturated TaC precursor

Tantalum carbide (TaC) matrix composites are widely used in aerospace thermal protection systems due to their high melting point and excellent thermal shock resistance. In the precursor infiltration and pyrolysis (PIP) process, the TaC precursor plays a critical role in the fabrication of the composites. However, conventional tantalum alkoxide precursors often suffer from insufficient crosslinking sites and lack of molecular-level mixing between the Ta and C sources. To address these issues, this study synthesized an unsaturated TaC precursor using tantalum pentachloride (TaCl 5 ) and 3-buten-1-ol as reactants, with allyl novolac resin (AN) introduced as the carbon source. The C=C bonds in the structure acted as active crosslinking centers during copolymerization, leading to the formation of a densely cross-linked network in the PTC-Butene precursor. Using PTC-Butene solution as the precursor and 30 vol% carbon fiber felt as the reinforcement, C f /TaC composites were successfully fabricated by PIP process. The composites were subjected to oxyacetylene ablation tests for 10, 60 and 120 s, and the ablation mechanisms were systematically investigated. Results show that during ablation, a molten Ta 2 O 5 layer formed on the surface, which acted as a barrier against oxygen diffusion. However, this oxide layer was continuously eroded by the high-speed gas flow. Carbon fibers helped alleviate thermal stress and suppress matrix cracking, yet inherent pores within the composites and channels left after fiber oxidation provided pathways for oxygen infiltration.