Ablation resistance of ZrC-MoSi2/ZrC-SiC double-layered coating in a plasma flame.

Graphical abstract Highlights • ZrC-MoSi 2 /ZrC-SiC double-layered coating with excellent ablation resistance is firstly reported. • SiC-depleted zone and bubble burst of MoO 3 were found to be the fatal defects for ZrC-SiC and ZrC-MoSi 2 coatings, respectively. • Diffusion phenomenon of Si from ZM layer into ZS layer was observed and active oxidation of SiC was limited. • Introduction of Si from decomposition of MoSi 2 into ZrC-SiC layer is a promising way to solve the problem of SiC-depleted zone. Abstract A double-layered composite coating was designed for optimizing the ablation resistance of ZrC coating, which contained external ZrC-SiC and inner ZrC-MoSi 2 layers. The ablation resistance of the coating was evaluated and compared with the single-layered ZrC-SiC and ZrC-MoSi 2 coatings. SiC-depleted zone and bubble burst of MoO 3 were found to be the fatal defects for the ZrC-SiC and ZrC-MoSi 2 coatings, respectively. For the double-layered coating, the external layer acted as oxygen diffusion barrier and the inner layer offered extra Si source for the external one. The double-layered design effectively reduced the destructive effect of SiC-depleted zone and bubble burst. [ABSTRACT FROM AUTHOR]