Ablation behavior of TaB2SiC coating for carbon/carbon composites under oxyacetylene torch

• Pack cementation was proposed to prepare TaB2SiC coating on C/C composites.
• Ablation behavior of the TaB2SiC coating was investigated under oxyacetylene torch.
• A glassy protective layer of TaSiO was formed on the surface.

To protect carbon/carbon (C/C) composites against ablation, a TaB2SiC coating was prepared on their surface by pack cementation. Ablation behavior of the coated C/C composites was investigated under oxyacetylene torch. After ablation for 30 s, the linear ablation rate of the TaB2SiC coated C/C composites was 4.2 μm/s. Compared with the SiC coated C/C composites and bare C/C composites, the linear ablation rate was reduced by 40% and 51%, respectively. During ablation, a mosaic-structured TaSiO glassy layer was formed, playing a positive role in preventing oxidizing species from attacking C/C substrate. Oxidation products of TaB2, existing as “pinning phases” in the coating, induced the deflection of the crack formed by the attack of oxyacetylene torch, which was beneficial to enhance the stability of TaB2SiC coating and improve the ablation resistance.