Improvement of the oxidation resistance of NiCrAlY coatings by the addition of rhenium

NiCrAlY coatings are commonly used to improve the oxidation resistance of gas turbine blade. In this research, the cyclic oxidation behavior at 1000 °C of NiCrAlY coatings with and without Re addition was investigated. XRD was used to identify the oxide phases formed on the coatings. The microstructural changes in the coatings during oxidation were examined by SEM, EDX and EPMA. The results indicate that the addition of Re decreases the oxidation rate of NiCrAlY coatings. After long-term oxidation, some less protective oxides (such as NiCr2O4 and NiAl2O4) were observed on the surface of the NiCrAlY coatings, while the scale formed on the NiCrAlYRe coatings was still composed of protective α-Al2O3. Therefore, it is concluded that the addition of Re clearly improves the oxidation resistance of NiCrAlY coatings in cyclic oxidation conditions.