Ellipsometric Study of Film Formation on Iron in Sodium Sulphate Solutions in the pH range 6–12

Szklarska-Smialowska, Susan; Mrowczynski, G.

doi:10.1179/000705975798320486

Cited by 20 publications

(4 citation statements)

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“…This suggests that the role of borate in solution is to stimulate nucleation of an oxide film whose presence may be a precursor to passivation. Previous work by Szkarska-Smialowska and Mrowczynski (18) suggests that when the air-formed oxide film on Fe is not completely removed prior to anodization in sulfate solution, traces of the remaining oxide are embedded in the growing salt layer and act as nuclei for pas- sive film formation. It is surprising that significant elements of a prior oxide film are able to remain on a rapidly dissolving Fe surface without being undermined.…”

Section: Time: (Eec)mentioning

confidence: 99%

“…The behavior of iron and steel in acidic systems has been investigated with various categories of inhibitors including quinolines and thioureas (5,6), sulfoxides (7-10), amides (11), acetylenic alcohols (12), propargylic alcohol (13)(14)(15), and triazoles (16) of which benzotriazole (BTA) has been found to be the most effective. Nobe and co-workers have investigated the effect of BTA on corrosion of Fe in acidic, neutral, and basic solutions (17)(18)(19). In acidic solution, they concluded that BTA inhibits by adsorbing and interfering with the cathodic evolution of hydrogen.…”

Section: The National Research Council Of Canada Assisted In Meeting ...mentioning

confidence: 99%

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Passivation of Iron in Sulfate, Perchlorate, and Borate Solutions: Role of Borate in the Passivation Process

MacDougall

Bardwell

1988

J. Electrochem. Soc.

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The anodic passivation of Fe has been investigated in borate buffer, sulfate, and perchlorate solutions. In sulfate and perchlorate solutions of either pH 3.0 or 8.4, the passivation process is highly inefficient with very large amounts of anodic charge passing before a Substantial decrease in current is observed. In these solutions, passivation appears to be associated with precipitation of a salt film and/or changes in the solution pH near the surface which permits the formation of a passive oxide. The efficiency for potential-step passivation cannot be significantly increased by changing the concentration of the supporting electrolyte, the pH of the solution from 3.0 to 8.4, or the potential of anodization. However, the addition of <5% pH 8.4 borate buffer to the neutral sulfate or perchlorate solutions results in a dramatic increase in the efficiency, with the anodic passivation charge decreasing by as much as two orders of magnitude. Similar trends are observed in pH 8.4 Na2SO4 solutions with previously passivated Fe electrodes which were cathodically reduced to different extents prior to anodization. The more of the prior film that remains on the surface before the anodic potential step in sulfate, the more efficient is the passivation process. The marked similarity of these results suggests that the beneficial action of borate towards Fe passivation is due to its ability to assist in the formation of the surface oxide film. While the pH buffering capacity of the borate can be playing a role, it is possible that borate buffer contains strongly interacting anions which give it an inhibiting capability. The interaction of these anions with the Fe surface is believed to stimulate formation of a surface oxide film, and this could explain the results in the present work. Passivation of Fe in sulfate and perchlorate solutions would be inefficient because these anions, unlike those derived from borate, do not have inhibitive abilities, nor do their soIutions have buffering capacity. The results indicate the important role played by prior oxide films, and the need for weli+defined starting surface conditions in passivation experiments.Studies of the passivation of Fe have generally been carried out in acid sulfate or neutral borate buffer solutions. During the last quarter century, the latter solution has been preferred because controlled cathodic removal of prior oxide films and highly efficient anodic passivation are possible in this electrolyte (1, 2). Since little or no Fe dissolution occurs during anodic treatment, in borate buffer, roughening of the electrode surface does not occur, making subsequent analysis of the surface (by ex situ techniques such as RHEED, Auger, XPS, SIMS, etc.) much easier. The borate buffer solution has become a standard electrolyte for studying the anodic behavior of Fe. On the other hand, there has been concern about work in sulfate solutions because of the possibility of SO42-adsorption interfering with passivation and the considerable amount of dissolution (as Fe 2+) resulting in ...

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Section: Time: (Eec)mentioning

confidence: 99%

Section: The National Research Council Of Canada Assisted In Meeting ...mentioning

confidence: 99%

Passivation of Iron in Sulfate, Perchlorate, and Borate Solutions: Role of Borate in the Passivation Process

MacDougall

Bardwell

1988

J. Electrochem. Soc.

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“…However, the same material may show passivity due to metal oxide film formed on the material surface in the same environment at relatively high potentials. According to Szklarska-Smialowska et al (25), the electrode potential influenced the films formed on the surface of iron in sodium sulfate solutions and the nature of the surface films affected the anodic behavior of iron. With applying a short time cathodic polarization, the open circuit potential for iron in NaHCO 3 solution could be stable at a certain negative potential.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Surface State on Electrochemical Behaviors of Iron in Slightly Alkaline Solutions

Chen¹,

Lu²,

Xiao³

et al. 2014

ECS Trans.

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The effect of prior cathodic polarization (PCP) treatment on the nature of the surface state and electrochemical behavior of iron in dilute bicarbonate solutions were studied. PCP treatment could cause a transition of open circuit state of iron from passive state to active dissolution state. The electrochemical impedance spectroscopy for iron in test solutions at open circuit state was significantly lower after the PCP treatment. Without PCP treatment, iron was in passive state and no obvious activepassive transition could be observed on anodic polarization curves in bicarbonate solutions with sulfate ion concentration less than 0.5 mol/L. After the PCP treatment, iron was in active dissolution state, and all anodic polarization curves exhibited active-passive transition characteristics.

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“…the portion of the anodic charge used in film formation) increases from <1% to values approaching 100%. Although it has been suggested that the remainder of the original oxide film might somehow interact with the developing salt film and/or act as nuclei for passive film formation in sulfate (2,4), there was no direct evidence that this was the case. Indeed, it seemed surprising that any part of a prior oxide could remain on such a rapidly dissolving Fe surface and not be undermined.…”

mentioning

confidence: 99%

Passivation of Fe in Sulfate Solutions: 18O/SIMS Evidence for the Participation of Preexisting Surface Oxide Films

MacDougall

Bardwell

Sproule

1988

J. Electrochem. Soc.

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Ellipsometric Study of Film Formation on Iron in Sodium Sulphate Solutions in the pH range 6–12

Cited by 20 publications

References 4 publications

Passivation of Iron in Sulfate, Perchlorate, and Borate Solutions: Role of Borate in the Passivation Process

Passivation of Iron in Sulfate, Perchlorate, and Borate Solutions: Role of Borate in the Passivation Process

The Effect of Surface State on Electrochemical Behaviors of Iron in Slightly Alkaline Solutions

Passivation of Fe in Sulfate Solutions: 18O/SIMS Evidence for the Participation of Preexisting Surface Oxide Films

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