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Cyclic Oxidation Behavior of Electrodeposited Ni3Al–CeO2Base Coatings at 850°C

“…10,16,28 The current electrodeposited Ni 3 Al base coatings during cyclic oxidation at 850 • C have shown similar behavior. However, the formation of alumina scales did not ensure good long-term cyclic-oxidation resistance for the coatings.…”

“…This inconsistency may arise from a higher pore density, more than 10 vol.% in the current Ni 3 Al base coatings, but only 8 vol.% in the Ni-Al coatings studied by Susan, and the different testing conditions. 10,26 The pores in the coating not only increase the exposed surface area but also act as stress enhancers in the presence of stresses. Residual stresses are commonly generated in the coating system due to the growth of oxide scale and the thermal cycling.…”

“…52 Si was reported to have little effect on the isothermal oxidation of Ni-Al coatings in air. 10,11 The effects of Fe and Mn on the oxidation of Ni 3 Al have not been reported so far. The effects of substrate elements due to interdiffusion on cyclic oxidation of the current Ni 3 Al base coatings are probably small as the content of these elements was low at the external surface of the coating, even after 1000 hr, according to EPMA analysis.…”

“…Izaki 1 first studied the high-temperature oxidation of such electrodeposited composite coatings. It was found that coatings with more than 16 at.% Al have superior short-term isothermal and cyclic oxidation resistance to 304 stainless steels at temperatures from 900 to 1100 • C. Susan 10,11 reported that the oxidation resistance of electrodeposited two-phase, γ -Ni+γ -Ni 3 Al, Ni-Al coatings was better than that of pure nickel and a two-phase Ni superalloy containing γ -Ni+γ -Ni 3 Al at 800 and 1000 • C. More recently, Zhou 3 conducted the short-term cyclic oxidation experiments on electrodeposited Ni-28 wt.%Al nanocomposite coatings at 1050 • C, where the oxidation rate were much lower than those of the nickel and the Ni-base superalloy.…”

“…Generally, electrodeposited Ni-Al coatings with low Al contents have satisfied long-term oxidation resistance at temperatures below 900 • C. 10 However, to achieve good oxidation resistance at higher temperatures, an increased Al content is required to form single-phase γ -Ni 3 Al or β-NiAl intermetallic coatings. Ni 3 Al intermetallic coatings have been received much attention due to fairly low weight gains during oxidation, even at temperatures above 1000 • C, carburization resistance, and sound resistance to oxidizing/chlorizing environments and molten salts.…”