M-site solid solution of vanadium enables the promising mechanical and high-temperature tribological properties of Cr2AlC coating

Abstract

Cr2AlC MAX phase coating exhibited excellent oxidation resistance and hot corrosion, but it typically suffered from low hardness and toughness as well as lack of lubrication at high temperature. With a solid solution design on M-site, we demonstrated that the hardness of the Cr2AlC MAX phase coating was enhanced by 34.3% when Cr was partially substituted with V (47 at.%), and the coating toughness was improved simultaneously. Furthermore, according to the high-temperature tribometer test, both the friction coefficient and the wear rate of the coatings at 900 °C against Al2O3 balls were significantly reduced at 47 at.% V. This could be attributed to the formation of a large number of molten V2O5 wrapped (Cr, Al)2O3 hard crystal grains, which not only provided a wide range of liquid-phase lubrication, but also prevented the coating from being apt to wear out. Different from the multi-phase compositing, this study suggested a promising strategy to enhance the combined mechanical and tribological performance of MAX phase coatings by M-site V solid solution for harsh applications at a high temperature of 900 °C.

Keywords

• Cr2AlC
• M-site solid solution
• Hard-yet-tough
• High-temperature friction