Oxidation Behavior of Vacuum Plasma Sprayed NiCoCrAlYTa Coating at 1050 ℃

NiCoCrAlYTa coating was prepared on DD6 single crystal alloy substrate by the vacuum plasma spraying (VPS) method. The oxidation behavior of DD6 substrate and DD6/NiCoCrAlYTa coating at 1050 ℃ was studied. The phase microstructure and microscopic morphology of the coating were studied by XRD and SEM. The results show that the oxidation kinetics curve of NiCoCrAlYTa coating conforms to the parabolic law, and the oxidation can be divided into two stages: fast oxidation and slow oxidation. The oxidation rate constant K of the fast oxidation stage is 0.006 52 mg²·cm⁻⁴·h⁻¹, and the oxidation rate constant of the slow oxidation stage is 0.002 74 mg²·cm⁻⁴·h⁻¹. In the slow oxidation stage, a relatively complete oxide protective layer was formed, which effectively reduces the further oxidation rate of the coating and substrate. The 200 h oxidation weight gain is 0.9 mg/cm², which is significantly lower than that of DD6 substrate which is 2.16 mg/cm². Therefore, NiCoCrAlYTa coating prepared by the VPS method has excellent oxidation resistance for the DD6 substrate below 1050 ℃.