期刊
CERAMICS INTERNATIONAL
卷 46, 期 12, 页码 20500-20509出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2020.05.155
关键词
FG-NiCrAlY/nano-CeO2 coating; Structural characteristics; Oxidation behavior; Diffusion
Conventional and CeO2-gradient NiCrAlY coatings (0.5-2.0 wt% of nano-CeO2 from the inner layer to layers adjacent to the outer surface) were produced by the high-velocity oxy-fuel spraying (HVOF) process. Microstructural characteristics, phases analysis and high-temperature oxidation behavior of the functionally graded (FG) NiCrAlY/nano-CeO2 coatings were investigated and compared with those monolayer (ML) NiCrAlY coatings with without CeO2 nanoparticles. The microstructure of the ML- and FG-coatings, as well as processed powders, were characterized using a transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), micro-hardness testing and Raman spectroscopy. On account of the calculation of oxidation behavior of the coating, the ML- and FG-coatings were exposed to laboratory's air at 1000 degrees C up to 100 h (short-term exposure) and 5000 h (long-term exposure) and moreover, the weight gain versus oxidation time and oxide growth rate were subsequently examined. Obtained results indicated that FG-NiCrAlY/nano-CeO2 coating had a better oxidation resistance as well as a lower oxide growth rate compared to the rest of the ML-coatings. In addition, increasing oxidation resistance of FG-NiCrAlY/nano-CeO(2 )coating can be attributed by controlling Al and O diffusion due to the formation of relatively thin, dense, and sticky Al2O3 oxide scale. Besides, all cases of the oxidized ML- and FG-coatings had a parabolic rate behavior owing to their diffusion-controlled oxidation under short- and long-term oxidation tests.
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