A study on the effect of nano-CeO2 dispersion on the characteristics of thermally-grown oxide (TGO) formed on NiCoCrAlY powders and coatings during isothermal oxidation

The present investigation is focusing on the high-temperature oxidation behavior of conventional and nano-CeO2 modified MCrAlY alloys, in the form of powders and coatings. Emphasis is placed upon the influence of MCrAlY alloy form on the oxidation performance. The NiCoCrAlY- CeO2 nanocomposite powders were prepared by mechanical milling and were subsequently thermally sprayed by high velocity oxygen-fuel (HVOF) technique. Isothermal oxidation tests were carried out at 1000 °C for up to 100 h. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) experimental analyses with thermodynamic equilibrium calculations were used for analysis of the oxide scales. The results indicated that the effect of nano-CeO2 addition on the oxidation properties was more pronounced in the form of coating. Moreover, the oxidation rate of the nano-CeO2 modified coating was found to be 87% lower than that of conventional coating, which was suggested to be related to the incorporation of nano-sized CeO2 dispersion into the Al2O3 scale. The different oxidation mechanisms were discussed. [Display omitted] •The nanocomposite NiCoCrAlY-CeO2 powders were prepared by mechanical milling.•The HVOF-sprayed coatings exhibited different oxidation behavior compared with the corresponding powders.•The beneficial effect of nano-CeO2 dispersion was more pronounced in the form of coating.