Multi-layered structural designs of MoSi2/mullite anti-oxidation coating for SiC-coated C/C composites

The gradient and laminated multi-layered MoSi2-mullite coatings were prepared with similar thickness by supersonic atmosphere plasma spraying (SAPS) on SiC coated C/C composites to analyze the effects of the two multi-layered structure on the oxidation resistance of SAPS MoSi2 coating under high temperature environment. Unexpectedly, the gradient multi-layered design showed almost no positive effect on the protective performance improvement in comparison to the monolayer MoSi2 coating. The laminated multi-layered design remarkably improved the oxidation resistance at 1500 degrees C, up to 226 h, as well as the thermal shock resistance to 30 thermal cycles with only half the mass loss of the monolayer one. Such obvious improvement in the laminated MoSi2/mullite multi-layered coating was attributed to the effect of macroscopic interfaces on the auxiliary self-healing and the change of thermal stress field, which were conducive to hindering further crack prolongation.

Automated summary

The gradient multi-layered design did not show significant positive effect on the protective performance improvement of SAPS MoSi2 coating. However, the laminated multi-layered design remarkably improved oxidation resistance and thermal shock resistance.