Relationship Between Conventional Pitting and Protection Potentials and a New, Unique Pitting Potential

Thompson, Neil; Syrett, B. C.

doi:10.5006/1.3315985

Cited by 62 publications

(24 citation statements)

References 2 publications

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“…4 shows the potentiodynamic anodic polarization curves of C-steel electrode in 1M H 2 SO 4 using different concentrations of NaCl at scan rate 1mVs -1 . The slow scan rate permits that the pitting initiation occurs at less positive potential [15]. It is clear from the results that in the concentration range of NaCl studied the metal does not exhibit an active-passive transition.…”

Section: Susceptibility Of C-steel To Pitting Corrosion By Chloride Ionsmentioning

confidence: 50%

Guar Gum as Corrosion Inhibitor for Carbon Steel in Sulfuric Acid Solutions

Abdallah

2004

Port. Electrochim. Acta

218

106

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Guar gum was tested as corrosion inhibitor for carbon steel in 1 M H 2 SO 4 solution using weight loss and Tafel polarization techniques. The results showed that the inhibition efficiency increases with the increasing of the guar gum concentration, which act as an inhibitor of the mixed type. The inhibition action of guar gum was discussed in terms of its horizontal adsorption on the metal surface. The adsorption follows Langmuir adsorption isotherm. The effect of the presence of chloride ion in pitting corrosion was analyzed by the potentiodynamic anodic polarization technique. The pitting corrosion potential changes with the concentration of Cl -ion according to a sigmoid S-shaped curve. This behaviour was explained on the basis of the formation of passivatable, active and continuously propagated pits.

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Section: Susceptibility Of C-steel To Pitting Corrosion By Chloride Ionsmentioning

confidence: 50%

Guar Gum as Corrosion Inhibitor for Carbon Steel in Sulfuric Acid Solutions

Abdallah

2004

Port. Electrochim. Acta

218

106

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“…Its apparent dependence on experimental parameters [7][8][9][10] led to its abandonment for many years as it was seen as not being a reliable material property. Extensive work from several groups [11][12][13][14][15][16] showed that when a sufficiently large anodic charge was passed during localized corrosion, the repassivation potential attains a value which is independent of charge passed for pit growth. Sridhar et al [15] demonstrated via extremely longterm (>5 years) potentiostatic tests that this plateau potential serves as an excellent lower bound for pitting corrosion.…”

Section: Introductionmentioning

confidence: 99%

Effects of environmental factors on key kinetic parameters relevant to pitting corrosion

Woldemedhin

Srinivasan

Kelly

2015

J Solid State Electrochem

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Experiments using stainless steel artificial pit (leadin-pencil) electrodes in ferric chloride and lithium chloride solutions were performed in order to determine the effects of key environmental factors such as chloride concentration and pH of the bulk solution on the central parameters utilized to characterize the pitting phenomenon-the repassivation potential E rp and the pit stability product under a salt film (i· x) saltfilm . For all the stainless steel alloys studied, a relative independence of the E rp to the pit depth was observed once sufficient anodic charge had been passed. The pit stability product under a salt film was seen to be largely insensitive to the pH of the bulk solution. E rp , on the other hand, was fairly independent of bulk pH only at the lower chloride concentrations of both lithium chloride and ferric chloride solutions. The two parameters were affected differently by variation in the chloride concentration of the bulk solutions. Increasing the chloride concentration resulted in a decrease in the value of (i·x) saltfilm for all alloys in both solutions. In ferric chloride, the value of E rp increased with increasing chloride concentration for Custom 465 and the austenitic steels, whereas it decreased across the same range for 17-4 pH. These trends were explained qualitatively using solution conductivity and alloying composition arguments. Finally, the results obtained from this study allowed for a rationalization of the phenomenology, enabling a method of measurement of the diffusion coefficient and the concentration at saturation of the Bstainless steel cation^within the pit, both of which agreed well with values obtained from the existing literature.

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“…7 Thompson and Syrett have suggested that the highest observed repassivation potential is the critical potential in pitting. 8 They indicated that this value is associated with repassivation of very small pits, and is close to the lowest observed value of pitting potential. No means was suggested, however, for accurate and reproducible determination of this critical potential.…”

Section: 2mentioning

confidence: 96%

“…2 may be considered to be critical potentials of the sort described by Thompson and Syrett. 8 A pit of a given size will only grow in a stable fashion if the potential is above the E R for a pit of that size, because only then is the pit current density sufficiently large to maintain the critical concentration for a pit of that size. The lowest potential for pit initiation may be the critical potential corresponding to the size of the initial defect.…”

Section: Discussionmentioning

confidence: 99%

Repassivation of Pits in Aluminum Thin Films

Frankel

Scully

Jahnes

1996

J. Electrochem. Soc.

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The effect of metal film thickness on repassivation of pits in sputter-deposited Al thin films was investigated in chloride solutions. The repassivation potential and the critical current density, which is the pit current density below which pits stop growing, were determined for pits in Al thin films ranging from 100 Ǻ to 43 µm in thickness. The repassivation potential first decreased as thickness increased from 100 to 4350 Ǻ, and then increased as the film thickness increased further. This behavior was found to be a consequence of the pit currentdensity/potential relationship. The critical current density, a more informative parameter, decreased for increasing metal film thickness, even when the repassivation potential increased. The critical current density is the minimum current density needed to maintain the critical pit environment and prevent repassivation. The repassivation potential for a given metal film thickness is the potential at which the pit current density drops below the critical value. Masstransport and ohmic resistance both increase as the metal film thickness increases, but the former enhances pit stability and the latter destabilizes pitting in this system. Pit repassivation, and thus stability, are strongly influenced by mass-transport considerations for pits in very thin pits, even though dissolution at low potentials is not under pure mass-transport control. Ohmic effects become increasingly important as the film thickness increases.

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Relationship Between Conventional Pitting and Protection Potentials and a New, Unique Pitting Potential

Cited by 62 publications

References 2 publications

Guar Gum as Corrosion Inhibitor for Carbon Steel in Sulfuric Acid Solutions

Guar Gum as Corrosion Inhibitor for Carbon Steel in Sulfuric Acid Solutions

Effects of environmental factors on key kinetic parameters relevant to pitting corrosion

Repassivation of Pits in Aluminum Thin Films

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