Oxygenated Treatment on Saturated Vapour Oxidation Behaviors of GH2984 Alloys for 700 °C Ultra-supercritical Boilers

The saturated vapor oxidation behavior of GH2984 alloys at 750 °C were investigated by oxidation weight increasing method, X-ray diffraction and scanning electronic microscopy in different dissolved oxygen concentrations. The results show that the oxide film of GH2984 alloys in different dissolved oxygen concentrations is of a single layer consisting of continuous Cr₂O₃. The oxidation mass gain of GH2984 alloys slightly increases with the increase of the dissolved oxygen concentrations in water vapor. Oxygenated treatment could accelerate the internal oxidation phenomenon, enhance the oxidation film thickness and make the scattered nodular bulges of Fe₂O₃ disappear and more Cr-rich nodular bulges form. Moreover, high dissolved oxygen concentrations do not affect the stabilization of Cr₂O₃ but contribute to the formation of a little Al₂O₃ and TiO₂ which are oxidized internally.