High-temperature reaction kinetics of Inconel 617 in impure helium

Abstract

Inconel 617 is the reference candidate material for the high-temperature gas-cooled reactor (HTGR) which is expected to contain traces of impurities in the primary circuit. The corrosion behaviors of Inconel 617 in a special impure helium atmosphere (PCO = 0μbar) were investigated at 750℃ and 980℃ in this work. The production of CO was observed above 830℃, which can be verified by the thermodynamic model of “microclimate reaction”. Compared with the corrosion phenomenon at 750℃, the oxide layer thinning, surface breakage, and mass loss were found at 980℃. Then, the reaction kinetics of this corrosion behavior at 980℃ was studied, and the influence factor controlling the reaction rate is the partial pressure of CO in the atmosphere. On this basis, a gas phase prediction model for the “microclimate reaction” is proposed, which can be utilized to predict the variation of CO content in the impure helium atmosphere during the corrosion process at 980℃. The model is in good agreement with the experimental gas data in this study and previous work. Further, the critical temperature of the microclimate reaction could be obtained by the kinetic model in this research, which is consistent with the previous results of thermodynamic calculation and corrosion experiments.

Keywords

• High-temperature corrosion
• Impure helium
• Inconel 617
• Reaction Kinetics