Electrochemical Noise Measurements on Carbon and Stainless Steels in High Subcritical and Supercritical Aqueous Environments

Abstract

The electrochemical noise induced in a pair of corroding carbon steel probes in simulated heat transport circuit fluids of a supercritical fossil-fueled power plant at temperatures up to 550°C and at pressures as high as 276 bar (4000 psi) was measured as a function of oxygen concentration, flow rate, temperature, and pressure. Additionally, electrochemical noise measurement (ENM) was explored as a means of detecting and monitoring stress corrosion cracking in sensitized Type 304 SS in high-temperature water (up to 288°C). Experimental results from these studies indicate that the electrochemical noise induced from corrosion of steels in high-temperature aqueous systems can be measured in a reproducible manner. The magnitude of the electrochemical noise responds sensibly to changes in the chemical and physical properties of the fluid, and the pattern of the electrochemical noise contains information on the nature of the corrosion processes that occur, including general corrosion, pitting attack, and stress corrosion cracking.