Microstructure and ablation behaviour of a strong, dense, and thick interfacial ZrxHf1-xC/SiC multiphase bilayer coating prepared by a new simple one-step method

In order to solve the shortcomings of chemical vapour deposition (CVD), such as CVD-prepared coatings that are weakly bound to the carbon base, ZrxHf1-xC/SiC multiphase bilayer ceramic coatings were prepared on substrate surfaces by slurry brushing and the one-step in-situ thermal evaporation reaction method. The coating exhibits multiphase bilayer characteristics due to the self-diffusion of the matrix carbon source and the self-assembly of gaseous Zr and Si with the matrix. The 200-μm-thick ZrxHf1-xC solid-solution phase is distributed on the outer coating layer, while the 100-μm-thick SiC phase is distributed in the inner layer such that it contacts the substrate. The coating prepared by brushing with Hf and vapour-deposited with a masterbatch containing 7:3 (w/w) Zr:Si (H-ST) exhibits excellent ablation resistance, attributable to the presence of dense and spallation-free oxide scale and the low oxygen diffusion coefficient of (Zr, Hf)CyOz.