Oxidation Behavior of NiCoCrAlY-ZrO₂·Y₂O₃ Coatings at 1100℃

NiCoCrAlY-ZrO2·Y2O3 coatings were deposited by the technology combining electron,atom and ion beams ( three beams).Isothermal oxidation was performed at 1 100 ℃ for 50 h,150 h and 300 h respectively.SEM with EDAX,as well as XRD were used to characterize the coatings.The results show that the oxidation behavoirs of the NiCoCrAlY-ZrO2·Y2O3 coatings obey the law of parabola.After oxidation at 1 100 ℃ the thickness of the ceramic layer became smaller,enrichment of chromium oxides form on the surface,and segregation of Y occurr at the surface due to its extra-diffusion with increasing oxidation time.The pinning of Y stabilize the chromium oxides at high temperature.Y play the main role in the oxidation resistance of the NiCoCrAlY-ZrO2·Y2O3 coatings.The brittle nickel and cobalt oxides on the surface spall and led to the depletion of aluminium oxides with the increase of time.The cross-section morphology of the coatings after oxidation 300 h show that good bonds between ceramic and alloy layers could be obtained for the coatings prepared with the technology of three beams.