Use of Multielectrode Arrays and Statistical Analysis to Investigate the Pitting Probability of Copper. Part I: The Effect of Chloride

Abstract

Under some conditions, copper and copper alloys are either immune from corrosion or undergo slow uniform corrosion, generally considered a favourable situation, because predicting the damage incurred by the metal during a period of uniform corrosion is relatively straightforward. However, under conditions leading to surface passivation of Cu, localized corrosion might occur in the presence of aggressive oxidants. Therefore, the susceptibility of Cu to localized corrosion must be considered carefully to avoid unpredictable failures in Cu-based structures. Understanding the pitting probability of Cu is important for various applications, including the use of Cu-coated containers for the permanent disposal of used nuclear fuel. In this study, the pitting probability of Cu in chloride-containing solutions crudely representing the groundwater that might be found in a deep geologic repository (DGR) was investigated using electrochemical techniques and statistical analysis. The probabilities of both pitting and repassivation of Cu were found to increase with increasing [Cl-]. The surface morphologies of copper electrodes in the same solution were also evaluated using scanning electron microscopy (SEM). The passive film on the surface of the copper electrode with the highest breakdown potential (Eb) was found to be more protective than that on the electrode with the lowest Eb

Susceptibility of copper to pitting corrosion in bicarbonate buffer solutions: Part I. Effect of chloride

“…Many studies have been performed to investigate the pitting of Cu in a range of environments, with corrosion parameters considered to be deterministic, not distributed 18,22,26,27,29,31,54,[65][66][67] . However, we showed the stochastic nature of corrosion parameters in our previous papers 73 . Here, we investigate the pitting probability, passive film morphology, and composition of oxide films in solutions with different chloride concentrations, using electrochemical, surface analysis, and statistical techniques to determine the pitting mechanism of Cu.…”

“…Histograms of Ecorr and Eb determined under passive conditions were plotted to facilitate the selection of applied potentials to be used in potentiostatic experiments. The applied potentials for potentiostatic experiments were chosen to be a) the maximum observed Ecorr value + 20 mV and b) the minimum observed Eb value -20 m V. These values were chosen to cover the tails of the Ecorr and Eb distribution curves where there are concerns about the pitting probability 73 . Eb was identified as the potential at which the current abruptly increased, and was determined from the intersection of the tangent to the current in the passive range and the rising current in the potential range after breakdown 69,74 .…”

Monitoring the galvanic corrosion of copper–steel coupling in bentonite slurry during the early oxic phase using coupled multielectrode arrays

“…[17] The use of multielectrode arrays using a multichannel microelectrode analyzer has also been demonstrated for copper pitting probability studies in chloride media. [18] From the current state-of-the-art review presented here, and the majority of recent research, [19,20] it is clear that several issues remain unanswered.…”

“…[ 17 ] The use of multielectrode arrays using a multichannel microelectrode analyzer has also been demonstrated for copper pitting probability studies in chloride media. [ 18 ]…”

Use of Multielectrode Arrays and Statistical Analysis to Investigate the Pitting Probability of Copper: Part II. The Effect of Sulfate and Bicarbonate

“…9,10,63,68 The corrosion behaviour of Cu in different environments, such as seawater and deaerated solutions, is well established. In addition, Matin et al 69 investigated the pitting probability of Cu in chloridecontaining solutions using multielectrode arrays and statistical analysis, but there is a lack of information regarding the susceptibility of Cu to pitting corrosion in sulfate-containing solutions. The majority of the published research has been conducted based on the hypothesis that corrosion parameters are deterministic, thus ignoring the effect of distributed values.…”