Electrochemical noise study on the corrosion behavior of 304NG stainless steel in high temperature water

Abstract

This paper investigates the application of Electrochemical Noise (EN) to study the corrosion behavior of 304 nuclear-grade (NG) stainless steel (SS) in high purity water system at varying temperatures (105, 160, 190, 220, 250, 293°C) and pressures (0.6, 7, 9, 10.5, 16, 19MPa). An EN sensor has been developed and applied to the high temperature water system. The potential and coupling current noise were recorded simultaneously and a variety of analytical methods (such as wavelet transform, chaos theory, noise resistance (Rn), the spectral noise resistance (Rsn) and the direct current (DC) limit of the spectral noise resistance (Rsn0)) have been used to obtain corrosion rate and corrosion form. EN analysis results demonstrated an increase in Rnwith increasing temperature and pressure, except for a peak value at 293°C, 19MPa, which was possibly due to the change in the thickness of passive film; combined chaos analysis results with morphology analysis, we may infer that the corrosion form of 304NG SS under high purity water system at high temperature and high pressure is general corrosion.