Study on oxidation resistance and Al diffusion of Cr1-xAlx coatings with different low Al content

Cr1-xAlx coatings with different low Al content were prepared on Zr alloy by magnetron sputtering. The influence of Al content on the microstructure, adhesion strengths, and oxidation resistance of the Cr1-xAlx coating was systematically evaluated. Air oxidation results show that a Cr91.4Al8.6 coating shows better air oxidation resis-tance. After steam oxidation tests, a Cr2O3-rich and Al2O3-rich double oxide layer is found to be formed in the Cr91.4Al8.6 coating. The Al2O3-rich layer can effectively prevent the surface Cr2O3 layer from being consumed by Zr diffusion along the Cr grain boundary and maintain stable double oxide structure. Moreover, the diffusion mechanism for the Al element during steam oxidation of the Cr91.4Al8.6 coating was analyzed in detail.