Effect of suspension plasma spraying power on the microstructure and properties of Cr2AlC coatings

In this work, the microstructure evolution and mechanical properties of suspension plasma sprayed Cr2AlC coatings under different spraying powers were studied, and a self-protection model during oxidation was proposed. Due to the partial decomposition of Cr2AlC and its subsequent reactions with the surrounding H2O or O2 at high temperatures, the sprayed coating exhibits a heat-resisting shell, composed mainly of Cr2Al, carbides, oxides, and graphite, wrapping the internal Cr2AlC core against further decomposition. In addition, with the increase of spraying power, the content of Cr2AlC phase and the microhardness of the coating gradually increase, while the porosity and surface roughness decrease. The results indicate that suspension plasma spraying is a promising process for preparing Cr2AlC coatings.