IR voltage switch in delayed crevice corrosion and active peak formation detected using a repassivation-type scan

AlZahrani, Abdullah A.; Pickering, H. W.

doi:10.1016/j.electacta.2004.12.017

Cited by 36 publications

(18 citation statements)

References 38 publications

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“…Several variables can change during the induction period and increase the IR product ͑e.g., pH, electrolyte cross section in the crevice, temperature, E x=0 ͒. 1,4 In this work two variables were observed to change in the experiment: the pH decreased from 9.1 to 3.5 and the amount of corrosion product increased in the crevice. As the pH decreases, the tendency is that both i pass ͑Fig.…”

Section: B28mentioning

confidence: 91%

“…Furthermore, since the pH for this system can decrease no lower than its equilibrium value, i.e., ϳpH 3.5, it is clear that crevice corrosion would never have occurred in this experiment by the chemistry change mechanism, since there is no other means in the chemistry change mechanism to increase the value of E A/P in order that it become as noble as the E x=0 value. Thus, only the IR mechanism as originally proposed, 5 i.e., IR voltage plus growth of an active peak and/or an increase in the passive current via one or more of a short list of other variables ͑including pH in these experiments͒, 4 can explain the onset of delayed crevice corrosion that is presented in Fig. 8 and 10 and elsewhere.…”

Section: B28mentioning

confidence: 96%

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Microprobe Study of pH during the Induction Period Preceding Crevice Corrosion

Wolfe¹,

Pickering²,

Shaw³

2006

J. Electrochem. Soc.

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Potential, pH, and their gradients are important parameters in determining the electrochemical reactivity of metals in crevices. Although an IR voltage alone can be responsible for the activation of crevice corrosion that occurs immediately, changes in pH may be necessary for crevice corrosion to occur in the delayed form of crevice corrosion. In cases where acidification forms an active peak in the polarization curve, pH, corrosion products, and electrode potential, E, inside the crevice play synergistic roles in determining the onset of crevice corrosion. This synergistic relationship is explored by measuring gradients in acidity, pH͑x͒, and electrode potential, E͑x͒, within crevices during the induction period preceding crevice corrosion of iron in 0.2 M Na 2 SO 4 + 0.025 M K 2 CrO 4 of pH 9.1. Crevice corrosion was found to initiate when the IR voltage caused the E͑x͒ to have a value within the active peak of the polarization curve of the crevice electrolyte. The active peak formed due to acidification of the crevice electrolyte.Crevice corrosion processes in metals and alloys belong to one of two groups: those that occur immediately upon contact with the electrolyte and those that occur after an induction period. This paper addresses the latter and focuses on the induction period, in particular how pH and electrode potential, E, change with time and distance, x, into the crevice, where x = 0 is at the opening of the crevice. E͑x͒ is given by the magnitude of the IR voltage at x, where I is the ionic current in the crevice electrolyte between x and x = 0 and R is the resistance over this distance. 1 In two cases of delayed crevice corrosion, one a spontaneously active system, 2 and the other a spontaneously passive system, 3,4 E at the bottom of the crevice, E x=L , sharply decreased at the same time as the current increased to the milliampere range, signaling not only the end of the induction period and start of the crevice corrosion but also the involvement of IR voltage. For the spontaneously passive system, an active peak formed in the polarization curve of the crevice solution during the induction period ͑its formation being caused by a decrease in pH͒. The large magnitude of the IR voltage, where R can increase significantly due to the formation of corrosion products ͑hydrogen gas, in this case͒ in the crevice, produced a value of E x=L that was in this newly formed active region. 4 Thus, E͑x͒ and active peak growth via a decreasing pH with time were instrumental in ending the induction period and starting crevice corrosion, in accord with the IR mechanism. 5 The so-called chemistry change or acidification mechanism could not explain this occurrence of crevice corrosion in that system ͑which is the same system as in this paper͒, because the active peak at the moment of the start of crevice corrosion was far too small to extend to the applied potential, E x=0 , i.e., the potential of the active/passive transition, E A/P , in the polarization curve of the crevice electrolyte was negative of E x=0 ͑by hund...

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Section: B28mentioning

confidence: 91%

Section: B28mentioning

confidence: 96%

Microprobe Study of pH during the Induction Period Preceding Crevice Corrosion

Wolfe¹,

Pickering²,

Shaw³

2006

J. Electrochem. Soc.

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“…Some methods have been proposed to study the mechanism of crevice corrosion including simulation of the crevice structure and the occluded environment [3], studying the changes in the chemical composition of the occluded solution [4] and measurement of the potential distribution inside the crevice by combination electrode [5] or multiple electrodes arranged linearly inside the crevice [6]. Briefly, two mechanisms exist for crevice corrosion: a chemical transformation mechanism [1,7,8] and an IR drop mechanism [9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical noise analysis on the crevice corrosion behavior of Ni–Cr–Mo–V high strength steel using recurrence plots

et al. 2010

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This article makes a study of electrochemical noise analysis on the crevice corrosion behavior of Ni-CrMo-V high strength steel using recurrence plots. The crevice corrosion behavior of Ni-Cr-Mo-V high strength steel was investigated by the electrochemical noise (EN) technique and SEM observation. The experimental results reveal that the crevice corrosion could be distinguished by three stages including induction stage, transformation stage, and stable stage. While increasing the growth probability of metastable corrosion, the presence of crevice decreases the initiation rate of metastable corrosion. In the case of crevice, the metastable corrosion is easy to develop into stable one.

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“…In some cases [8], e.g., Ni in sulfuric acid [9], the active peak originally exists in the polarization curve and immediate crevice corrosion ensues. In contrast, in less corrosive environments [10] or for more corrosion-resistant alloys [11,12], an incubation period is required for the active peak to appear. This can occur when i) the passive current increases [13] or metastable pitting gives raise to current (I increases), ii) the potential range of the active peak increases (EA/P increases) due to an increase in temperature or a change in the electrolyte composition (pH [14], chlorides), iii) R increases due to the formation of constriction by gas bubbles or corrosion products [15], or iv) the corrosion potential of applied potential ESURF shifts in the negative direction.…”

Section: Introductionmentioning

confidence: 99%

Crevice Corrosion of Stainless Steels 904L, 2205, and 2507 in High-Temperature Sulfuric Acid Solution Containing Chlorides: Influence of Metal Cations

et al. 2017

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Crevice corrosion of stainless steels 904L, 2205 and 2507 in high-temperature sulfuric acid solution containing chlorides: Influence of metal cations (2018). Crevice corrosion of stainless steels 904L, 2205 and 2507 in high-temperature sulfuric acid solution containing chlorides: Influence of metal cations. Corrosion, 74(2), 225-240. https://doi. AbstractCrevice corrosion influences the integrity of materials in many industrial sectors, such as hydrometallurgy. The conditions in hydrometallurgical processes are severe, with high concentrations of sulfuric acid leachant as well as high chloride impurity, oxygen and metal cation contents. In this study, crevice corrosion behaviour of highly-alloyed austenitic and duplex stainless steels is investigated in aerated high-temperature sulfuric acid solution with 1 g/l chlorides in the presence of three types of metal cations: Fe 3+ , Cu 2+ , and Fe 2+ . The experimental work contained determination of the oxidizing capacity of the solutions, immersion crevice corrosion tests followed by characterization of the corrosion attack, and potentiodynamic polarization measurements. The results showed that the alloy with the highest PREN-value, 2507, was not susceptible to crevice corrosion under the test conditions. In the case of alloys 904L and 2205 of relatively equal PRENvalues, the extent and nature of crevice corrosion attack was different and dependent on the ratio 2 of activities of chlorides to sulfates and the type of metal cations. The results are presented and discussed in the light of IR drop mechanism.

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IR voltage switch in delayed crevice corrosion and active peak formation detected using a repassivation-type scan

Cited by 36 publications

References 38 publications

Microprobe Study of pH during the Induction Period Preceding Crevice Corrosion

Microprobe Study of pH during the Induction Period Preceding Crevice Corrosion

Electrochemical noise analysis on the crevice corrosion behavior of Ni–Cr–Mo–V high strength steel using recurrence plots

Crevice Corrosion of Stainless Steels 904L, 2205, and 2507 in High-Temperature Sulfuric Acid Solution Containing Chlorides: Influence of Metal Cations

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