Investigations into Power Plant Alloys’ (Inconel 718) Oxidation Resistance by Compound Composite (Cr2O3 + YSZ) Coatings

Abstract

As it increases the pressure and temperature of incoming steam and decreases CO2 emissions, oxidation is crucial for materials used in power plants to increase their efficiency. Compound composite (Cr2O3 + YSZ) coatings applied to Inconel 718 (EN8) substrates using the Atmosphere Plasma Spray technique are anticipated to increase structural resistance when subjected to high pressure and temperature oxidation conditions of service. The nickel-based superalloys EN8 and EN8/Yttria (8% Y2O3) Stabilized Zirconia (YSZ)/Cr2O3 were subjected to high-temperature oxidation tests in the open air at 1050 °C for approximately 12, 24, 48, and 100 h. EN8 is not appropriate for prolonged use at 1050 °C as can be seen from scanned electron microscope and energy dispersive X-ray spectroscopy analyses on isothermally oxidized samples. The findings demonstrated that the EN8 alloy exhibited more significant weight variations over 48 h at high temperatures because its chromia oxide scale was continuously smaller. With phase dispersion in the microstructure, coated EN8 exhibits a higher performance under more prolonged exposure than the EN8 alloy. Additionally, the synthesis of outer chromium oxide, YSZ, and Cr2O3 on a substrate at 1050 °C for 100 h improved the outstanding oxidation resistance while maintaining the integrity of the chromium oxide layer.