High-Temperature Antioxidant Property of NiCoCrAlY/AlSiY Composite Coating on the Surface of GH907 High-Temperature Alloy by Arc Ion Plating

To improve the high-temperature oxidation resistance of GH907 high-temperature alloy at 750°C, NiCoCrAlY/AlSiY composite coatings were prepared on the surface of GH907 alloy by arc ion plating (AIP) technique. We systematically studied the high-temperature antioxidant behaviors and mechanisms of composite coatings. Micro-scale analytical characterization methods such as XRD, SEM and EDS were used to comprehensively analyze the physical phase structural characteristics, oxidation product compositions, and surface/cross-section topographic features during the oxidation process. Tests showed that after oxidation at 750℃ for 500 h, the oxide layer (FeO, Fe₂O₃) of GH907 high-temperature alloy sprouted a large number of cracks, and the oxide layer occurred a large area of spalling. The substrate showed a tendency to rapidly oxidize and gain weight, with a mass gain value of 22.38 mg/cm² for 500 h. In contrast, NiCoCrAlY/AlSiY composite coating in the oxidation experiment, due to the formation of continuous and dense Al₂O₃ barrier layer, the internal diffusion of oxygen was effectively inhibited, reducing the oxidation reaction impact of GH907 high-temperature alloy. The mass gain of oxidation 80 h was 6.37 mg/cm², then the mass gain rate tended to stabilize, and the mass gain of 500 h composite coating was only 7.68 mg/cm². In conclusion, it showed that the NiCoCrAlY/AlSiY composite coating can significantly improve the high-temperature oxidation resistance of GH907 high-temperature alloy.