Ablation behavior and mechanism of SiC/Zr-Si-C multilayer coating for PIP-C/SiC composites under oxyacetylene torch flame

To improve the ablation resistance of PIP-C/SiC composites, SiC/Zr-Si-C multilayer coating was prepared by chemical vapor deposition (CVD) using methyltrichlorosilane (MTS) and hydrogen as the precursors and molten salt reaction using KCl-NaCl, sponge Zr and K2ZrF6, then the ablation capability of the coated composites was tested under oxyacetylene torch flame. The linear and mass ablation rates were much lower than those of uncoated samples. The linear and mass ablation rates of the three coating coated samples reached 0.0452 mm/s and 0.031 g/s, decreased by 27.3% and 27.1%, respectively. Moreover, the linear and mass ablation rates of the five coating coated samples reached 0.0255 mm/s and 0.0274 g/s, decreased by 59.0% and 35.5%. The gases released during ablation could take away a lot of heat, which was also helpful to the protection of the composites.