Corrosion-mechanical property interaction of Ni- and Fe-base alloys in high temperature supercritical-CO2 environment

Abstract

The supercritical-carbon dioxide (S-CO$_2$) Brayton cycle has emerged as a cross-cutting power conversion technology that could potentially be used for various energy applications such as next generation nuclear, fossil, and concentrated solar power plants. Meanwhile, long-term compatibility of structural materials in high temperature S-CO$_2$ environment would be crucial for successful implementation of the S-CO$_2$ cycle. In this thesis, creep property of a Ni-base alloy was evaluated in S-CO$_2$ environment at 650 $^o$C (20 MPa). Then, oxide analyses were performed on the crept specimens to evaluate the interaction between corrosion and creep behavior in high temperature S-CO$_2$ environment. Furthermore, it was demonstrated that appropriate control of S-CO$_2$ chemistry can result in improvement in both corrosion resistance and creep rupture lifetime. Finally, the effect of high temperature S-CO$_2$ exposure on mechanical integrity of diffusion-bonded joints of Fe- and Ni-base alloys was evaluated.