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.

An in-situ conductometric apparatus for physicochemical characterization of solutions and in-line monitoring of separation processes at elevated temperatures and pressures

“…Above all, complex resistance (impedance) spectra provide a wealth of information/insight. The low-frequency response can be utilized for rapid evaluation of material corrosion [6,7], diffusion characteristics of solutes [8], and structural characteristics of the double layer [9]. As the excitation frequency increases, the real part of the impedance decreases, whereas its imaginary part increases.…”

Reliable electrochemical phase diagrams of magnetic transition metals and related compounds from high-throughput ab initio calculations

“…Numerous mTM alloys and compounds have been applied broadly and frequently throughout history. Various conventional mTMbased structural alloys (e.g., Fe and Ni alloys) are widely used in many low-and high-temperature fields, including civilian tools, construction frameworks, biocompatible alloys, [1][2][3] gas turbines, [4][5][6] and nuclear-power equipment, [7][8][9] owing to their excellent mechanical properties, environmental benignity, and oxidation and corrosion resistances. Superior mechanical properties are also present in mTM-based high-entropy alloys, [10][11][12] and their corrosion resistance is under intensive investigation due to its importance.…”