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

• Published in: Journal of alloys and compounds 2020-09, Vol.835, p.155319, Article 155319
• Main Authors: Zakeri, A., Bahmani, E., Sabour Rouh Aghdam, A., Saeedi, B., Bai, M.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Cerium oxides; Coatings; Dispersion; Electron microscopy; High temperature; High-temperature oxidation; HVOF; MCrAlY; Mechanical milling; Microscopy; Nanocomposite; Nanocomposites; NiCoCrAlY; Oxidation; Oxidation rate; Oxidation tests; Scale (corrosion); Thermodynamic equilibrium
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.155319

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.