Effect of chloride concentration and temperature on growth of 1D Pit

Jun, Jiheon; Frankel, G. S.; Sridhar, Narasi

doi:10.1007/s10008-015-2780-4

Cited by 28 publications

(52 citation statements)

References 21 publications

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“…37 Furthermore, Ernst and Newman, 29 Jun et al, 36 and Woldemedhin et al 27 have shown that modeling the transport characteristics of the 1-D pit corroding under a salt film purely as a diffusion-limited process with the value for D as reported by Gaudet et al 14 25 to be independent of pit diameter. Also, studies by Novakovski and Sorokina, 38 and later by Isaacs 18 have shown that the majority of this potential drop occurs across the salt film, and the current in the pit is primarily regulated by diffusion.…”

Section: Methodsmentioning

confidence: 92%

“…26,27,29,36 Also, the assumption of constant diffusivity has been shown by Gaudet et al 14 to effectively approximate the combined effects of variable diffusivity and electromigration on the cation flux.…”

Section: Methodsmentioning

confidence: 99%

“…29,36,44 In toto, the results shown in Figures 9 through 13 demonstrate that it is imperative to account for the effects of both pit depth as well as bulk electrolyte chemistry during measurement and analysis of artificial pit studies to obtain accurate estimates of pit stability parameters. 14 is considered (reproduced in Figure 14).…”

Section: Bulk [Clmentioning

confidence: 98%

“…This result may be reflective of the fact that viscosity effects on physicochemical parameters play an increasingly important role in determining mass transport as the bulk chemistry becomes more concentrated in chloride, as reported in the literature. 19,29,36,44 Such effects on solution properties may have an impact on both D as well Figure 11. Numerically simulated concentration at the pit mouth for a generalized 1-D pit.…”

Section: Bulk [Clmentioning

confidence: 99%

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Geometric Evolution of Flux from a Corroding One-Dimensional Pit and Its Implications on the Evaluation of Kinetic Parameters for Pit Stability

Srinivasan

Liu

Kelly

2016

J. Electrochem. Soc.

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The flux from a one-dimensional (1-D) artificial pit electrode corroding under a salt film was examined using experimental and modeling techniques. Finite element simulations showed that the flux at shallow depths was consistently lower than analytically determined calculations for 1-D Fickian diffusion. This deviation was due to a substantial contribution of the external hemispherical boundary layer to the overall diffusion length. Increasing the pit diameter resulted in a larger boundary layer, which in turn affected the flux characteristics to greater depths. Data from experiments and simulation converged with the theoretical 1-D calculations only when pit depths approached nearly ten times the pit diameter. The experimental data from this artificial pit study as well as data from related published work were observed to span the range bounded by the numerically simulated and the analytically determined flux predictions. Comparison with published pit stability phenomenology showed that only deep pits provided kinetic data based on the cation concentration gradient unadulterated by bulk chloride effects. Finally, this work also provided insight into the origin of the dependence of the measured repassivation potential with pit depth, contributing towards a quantitative framework relating the various critical factors governing pitting. The stable growth of corrosion pits requires the presence of an aggressive chemistry at the corroding surface as characterized by a high metal chloride concentration and low pH.1,2 The conditions leading to the maintenance of such chemistry were mathematically considered by Galvele 3 through an investigation of the steady state relationship between metal dissolution and mass transport 4,5 out of a one-dimensional (1-D) pit. For the case of a 1-D pit, it was theoretically demonstrated that a minimum critical value of cation flux -expressed as the product of the current density and the pit depth, (i·x) -was necessary for the pit to maintain a critical chemistry and thus stably corrode. As such, should the product of the current density and the pit depth fall below this critical value, repassivation would set in due to the loss of the aggressive chemistry. Subsequent studies on stainless steel pitting referred to this parameter and equivalent relationships for other pit geometries as the pit stability product. 6,7 This critical pit stability product (denoted (i·x) crit ) has been employed as the anodic stability parameter to determine the maximum pit size that can be attained on a particular metal surface in a given corrosive environment. 8-11Experimental results obtained using the artificial pit or lead-inpencil electrode 12-17 can be directly used to quantify 1-D dissolution kinetics because the construction of this electrode results in inert walls surrounding a single active surface 13,14,16 corroding under a precipitated salt film 18-24 upon the application of high anodic potential in corrosive solution. The presence of the salt film results in diffusionlimited dissolution conditi...

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Section: Methodsmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Bulk [Clmentioning

confidence: 98%

Section: Bulk [Clmentioning

confidence: 99%

See 2 more Smart Citations

Geometric Evolution of Flux from a Corroding One-Dimensional Pit and Its Implications on the Evaluation of Kinetic Parameters for Pit Stability

Srinivasan

Liu

Kelly

2016

J. Electrochem. Soc.

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“…4 The value of D is taken to be 8.24 × 10 −6 cm 2 /s, a value close to that of Fe +2 in 1 M HCl, 87 that has been shown to be a reasonable approximation of the effective diffusion coefficient of the 'stainless steel cation' in multiple studies. 7,42,54,73,82,84 The expression in Equation 4 is relevant to the boundary condition that considered the flux at the corroding surface to be zero.…”

Section: Discussionmentioning

confidence: 99%

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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Passivation of X65 steel in NaHCO₃ solution saturated with CO₂ using thin wire specimens

Shang

et al. 2017

Materials & Corrosion

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The passivation of X65 steel in NaHCO3 solution saturated with CO2 was investigated using electrochemical and immersion tests as well as surface morphology and composition analysis. The tests were conducted using thin wire specimens at atmospheric pressure in NaHCO3 solution with different concentrations and at different temperatures. The electrochemical properties of thin wire specimens and square specimens were compared. Thin wire specimens were immersed for a long period, during which the open circuit potential (OCP) was recorded. Anodic polarization was performed after the OCP was sufficiently high and stable. Electrochemical tests revealed that the electrochemical properties of the thin wire specimens were consistent with those of the square specimens. A sudden increase in the OCP of approximately 700 mV occurred after the specimens were immersed for a long period in the tested concentration and temperature. The time at which the OCP increase occurred decreased when the NaHCO3 concentration or temperature were increased. After the OCP became stable, anodic polarization revealed favorable self‐passivation. Immersion tests on X65 steel demonstrated that the OCP increase may have been due to the filling of pores between FeCO3 grains. Small tetrahedron grains formed in the pores of large hexahedral grains to lower the porosity of the film, thus making the film more compact. Consequently, the OCP increased and anodic polarization presented self‐passivation.

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Effect of chloride concentration and temperature on growth of 1D Pit

Cited by 28 publications

References 21 publications

Geometric Evolution of Flux from a Corroding One-Dimensional Pit and Its Implications on the Evaluation of Kinetic Parameters for Pit Stability

Geometric Evolution of Flux from a Corroding One-Dimensional Pit and Its Implications on the Evaluation of Kinetic Parameters for Pit Stability

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

Passivation of X65 steel in NaHCO₃ solution saturated with CO₂ using thin wire specimens

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Effect of chloride concentration and temperature on growth of 1D Pit

Cited by 28 publications

References 21 publications

Geometric Evolution of Flux from a Corroding One-Dimensional Pit and Its Implications on the Evaluation of Kinetic Parameters for Pit Stability

Geometric Evolution of Flux from a Corroding One-Dimensional Pit and Its Implications on the Evaluation of Kinetic Parameters for Pit Stability

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

Passivation of X65 steel in NaHCO3 solution saturated with CO2 using thin wire specimens

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Product

Resources

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Passivation of X65 steel in NaHCO₃ solution saturated with CO₂ using thin wire specimens