Abstract
The effects of vacuum pre-oxidation treatment on the isothermal and cyclic oxidation behaviour of a cold-sprayed NiCoCrAlY coating are investigated. It is found that the cold-sprayed NiCoCrAlY coating has a dense structure with low oxygen content and consists of a single γ-matrix phase. A uniform and continuous α-Al2O3 layer with a thickness of 0.47 ± 0.02 μm can be obtained by pre-oxidation treatment in a vacuum environment. The pre-oxidation treatment decreases the growth rate of thermally grown oxide by the formation of Al2O3 with larger grain sizes and thus improves the thermal cyclic life of coating. Surface-geometry imperfections are the source of initial spallation of thermally grown oxide.
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