The dissolution and repassivation kinetics of Fe-Cr alloys in pit solutions

Steinsmo, Unni; Isaacs, H.S.

doi:10.1016/0010-938x(93)90136-5

Cited by 22 publications

(19 citation statements)

References 5 publications

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“…Hence, we have applied an IR correction such that each line shows the current density that would have been reached if the surface potential at all points was equal to the maximum surface potential actually reached at any one point along the actively corroding pit perimeter at that time. Figure 2 is similar to those produced by Gaudet et al 9 and subsequent researchers 21,22 . As shown by these previous works, there is a steep decrease in anodic current density as the metal ion concentration falls below about 65% of saturation, which marks the well-known "critical local chemistry" for pit propagation.…”

Section: Resultssupporting

confidence: 83%

(Invited)Localized Dissolution Kinetics From Fast In Situ Radiography of Propagating Pits in Stainless Steel and Implications for Modeling Pitting Corrosion over Long Time-Scales

Laycock

Krouse²,

Ghahari

et al. 2012

ECS Trans.

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In-situ synchrotron radiography has been used to observe propagating 2D pits in a thin foil of 304 stainless steel sandwiched between glass slides. Key kinetic parameters have been extracted from these radiographs such that they can be used as input parameters for numerical simulations of pitting corrosion. Simulation results are presented for pits growing under potentiostatic control, with a focus on propagation stability in the concentrated (> 1M) chloride solutions that cause atmospheric pitting corrosion of 304 stainless steel.

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Section: Resultssupporting

confidence: 83%

(Invited)Localized Dissolution Kinetics From Fast In Situ Radiography of Propagating Pits in Stainless Steel and Implications for Modeling Pitting Corrosion over Long Time-Scales

Laycock

Krouse²,

Ghahari

et al. 2012

ECS Trans.

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“…7. This plot is similar to those produced by Gaudet et al 4 and subsequent researchers, 7 23 7,23,24 except that the data in Fig. 7 have not been corrected for the external IR drop.…”

Section: Resultssupporting

confidence: 81%

Pitting corrosion of stainless steel: measuring and modelling pit propagation in support of damage prediction for radioactive waste containers

Ghahari

Krouse²,

Laycock

et al. 2011

Corrosion Engineering, Science and Technology

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In situ synchrotron radiography has been used to observe the evolution of two-dimensional pits growing in stainless steel foils under electrochemical control in chloride solutions. A method for extracting the key kinetic parameters from radiographs is under development to provide data for validating and calibrating a two-dimensional finite element model previously developed by Laycock and White. The local current density along the boundary of a pit is directly measured from the radiographs. Then, the local metal ion concentration and potential drop inside the pit cavity are backcalculated using transport equations and the requirement to maintain charge neutrality, giving the relationship between current density, solution composition and interfacial potential. Preliminary comparisons show qualitative correlation between the model and extracted data; quantitative comparison is under way.

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“…The ambiguity in identifying a critical surface concentration because of multiple intermediate steady states 7,42 is avoided in this study which provides a single value of the critical solution chemistry and relates it to a critical potential E rp defined with respect to a critical diffusion flux. Therefore, an intermediate solution chemistry is identified at which not only are both dissolution and dilution fluxes equal, but also the associated potential represents a critical measure of the repassivation condition.…”

Section: Discussionmentioning

confidence: 99%

“…This reasoning motivated attempts by Isaacs and coworkers to identify such film-free steady-states. 4,7,42 The results of these studies indicated the presence of such states associated with several surface concentrations, thereby demonstrating that single, unambiguous critical values for the surface concentration and the associated potential at which stable pitting was sustained could not be extracted. Nonetheless, these data provided the commonly accepted range of 60% to 80% of metal chloride saturation as the critical surface concentration which has informed the view of many authors investigating pitting stability as a function of chloride concentration.…”

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confidence: 98%

One-Dimensional Pit Experiments and Modeling to Determine Critical Factors for Pit Stability and Repassivation

Srinivasan

Kelly

2016

J. Electrochem. Soc.

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Experiments on stainless steel artificial pit electrodes in sodium chloride were used to inform a diffusion model developed based on the mass transport behavior within a one-dimensional corroding pit. Measurable estimates of the dissolution flux as well as the potential describing the conditions of interest were obtained from experiment as the one-dimensional pit stability product under a salt film (i · x) saltfilm and the repassivation potential E rp , respectively. These parameter estimates were acquired as a function of pit depth and were related to the concentration of the metal cation at the corroding surface at each depth via a one-dimensional mass transport model. These results allowed for the construction of a quantitative framework relating the various electrochemical parameters describing the transition from pit stability to repassivation. Such an analysis permitted the straightforward estimate of the critical surface concentration associated with this transition, which resulted in a single conservative lower bound of 50% of the saturation concentration for the minimum aggressive chemistry to sustain stable pitting and prevent repassivation. Along with published data, these results were utilized to advance the idea that the critical pit solution chemistry is independent of bulk chloride concentration up to 4 M, a range frequently encountered in atmospheric conditions. © The Author Many authors have separately reported the critical electrochemical conditions necessary for stable pitting and repassivation, focusing on dissolution flux, 1-8 pit solution chemistry, 9-16 or potential. 17-31The existence of these critical parameters is predicated upon the steady-state relationship that emerges between two competing processes. These processes are i) metal dissolution and hydrolysis that results in a local aggressive chemistry inside the pit, and ii) the dilution of this chemistry by diffusion out of the pit that contributes to repassivation. [32][33][34] The mathematical description of this relationship for a one-dimensional pit was framed by Galvele 1 in terms of the product of the current density and the pit depth, (i · x), which was termed the pit stability product in later studies. [35][36][37][38] Once this product decreased below a critical value, (i · x) crit , the conditions in the pit would no longer be able to sustain the local aggressive chemistry necessary for active dissolution. Galvele's formulation, originally intended to describe the conditions leading to pit initiation, has also been successfully extended to pit propagation. 4,7,[35][36][37] Experimental assessment of the Galvele pit model is typically performed using the artificial pit or lead-in-pencil electrode, 4,7,[39][40][41][42] which consists of a metal wire embedded in epoxy. The lead-in-pencil electrode is particularly useful because it closely represents Galvele's pit model configuration, i.e. a single activated surface and inert walls. 7,8 Additionally, the precipitation of a salt film 40,[43][44][45][46][47][48] at high anodic po...

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The dissolution and repassivation kinetics of Fe-Cr alloys in pit solutions

Cited by 22 publications

References 5 publications

(Invited)Localized Dissolution Kinetics From Fast In Situ Radiography of Propagating Pits in Stainless Steel and Implications for Modeling Pitting Corrosion over Long Time-Scales

(Invited)Localized Dissolution Kinetics From Fast In Situ Radiography of Propagating Pits in Stainless Steel and Implications for Modeling Pitting Corrosion over Long Time-Scales

Pitting corrosion of stainless steel: measuring and modelling pit propagation in support of damage prediction for radioactive waste containers

One-Dimensional Pit Experiments and Modeling to Determine Critical Factors for Pit Stability and Repassivation

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