The Estimation of Local Anodic Current by the Reverse Application of the Corrosion Potential Fluctuations

Abstract

Corrosion potential fluctuation of SUS 304 stainless steel during induction period of localized corrosion was measured in 4.0 mol/l NaCI solution. The solution was exposed to air and its temperature was kept at 353K. It was found that new type of the potential fluctuation (Type II), differ from the potential fluctuaiton generally reported (Type I). From the result of SEM observation, the number of Type II and the number of micropits were agreed. In order to investigate the correlation between potential fluctuation and micropit, it was thought up that new method to estimate the local anode current quantitatively from the observed potential fluctuation. The observed corrosion potential fluctuation was applied to the specimen by a potentiostat and the change of the cell current (response current) was measured. Pit radius estimated from the integral of the response current was in good agreement with the radius of micropit evaluated from SEM micrograph.

Long term integrity against corrosion of titanium used for TRU waste container

“…This quantity for the destruction and recovery of passive film Q r versus time to repassivation t r appears in Fig. 3 along with the trapezoidal wave load test and the destruction results for passive film2 and immersion test data for stainless steel in a sodium environment 3. The electric quantity density versus time based on i pass of 10 −3 A m −2 is also given in the figure.…”

“…3 along with the trapezoidal wave load test and the destruction results for passive film 2 and immersion test data for stainless steel in a sodium environment. 3 The electric quantity density versus time based on i pass of 10 23 A m 22 is also given in the figure. This parameter, which extends beyond the line of 10 23 A m 22 , was used for passive film destruction and repassivation.…”

Application of magnetic phenomena to analysis of stress corrosion cracking in welded part of stainless steel

“…It is desirable to be able to detect SCC cracks easily and nondestructively before or just after crack initiations for enhancement of safety of nuclear power plants and more rational lifetime prediction. Although some nondestructive inspection methods for initial SCC cracks have been proposed until now [1][2][3], it is difficult for any of those methods to come into practical use. Since they use pulse signals such as electrochemical noise and acoustic emission measured when SCC cracks initiate and propagate, they require full-time monitoring with many sensors.…”

Monitoring of stress corrosion cracking in stainless steel weldments by acoustic and electrochemical measurements

“…Another useful technique of SCC monitoring is the corrosion potential fluctuation (CPF). This technique is also called electrochemical noise analysis (ENA) [10]. A high resolution (µV) monitoring system of the CPF can detect the initiation of localized corrosion [10,11].…”

“…This technique is also called electrochemical noise analysis (ENA) [10]. A high resolution (µV) monitoring system of the CPF can detect the initiation of localized corrosion [10,11]. Non-faradic reactions due to local anodic dissolution are reported to cause characteristic potential fluctuations.…”