Accelerated estimation of corrosion rate in supercritical and ultra-supercritical water

Abstract

This study explores a methodology for the determination of the accelerated corrosion rate of candidate materials to be used in advanced supercritical and ultra-supercritical water-based thermal reactors. Electrochemical impedance spectroscopy and electrochemical frequency modulation were used to evaluate the corrosion rates of SAE 316 stainless steel, Nitronic 50, Inconel 718, and Inconel 625 in supercritical water at 530 °C and in ultra-supercritical water at 600 °C. The results were compared to the results of gravimetric studies that were performed to determine the viability of the utilization of electrochemical analyses in supercritical and ultra-supercritical water. For all of the conditions that were tested, results showed that the corrosion rates during electrochemical testing had trends that were similar to the long-term gravimetric results. Thus, the hybrid methodology described in this manuscript can reduce testing times from >1000 h to ~ 10 h.