Effect of Chloride Ion on the Localized Breakdown of Nickel Oxide Films

MacDougall, B.

doi:10.1149/1.2129194

Cited by 114 publications

(63 citation statements)

References 32 publications

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“…The former gives a pitting potential which is usually a function of sweep rate (8), while the latter gives an induction time for pit initiation at a specific potential. The potentiodynamic approach is illustrated in Fig.…”

Section: Resultsmentioning

confidence: 99%

Influence of Incorporated Cl− in NiO on the Pitting Susceptibility of Nickel

MacDougall

Graham

1984

J. Electrochem. Soc.

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The pitting susceptibility of nickel in 0.08M C1-solutions (pH 4.0 Na2SOD has been determined by both potentiodynamic and potentiostatic techniques, the former giving a pitting potential and the latter an induction time, rind, for pit initiation. The potentiostatic approach is preferred because of the good reproducibility of results. Samples were prepassivated in non-C1-or C1-containing solutions and then potentiostatically polarized in 0.08M CI-at different potentials and rind measured. For either pretreatment, r~nd decreased exponentially as the potential of pitting increased, i.e., log 1/r ~V. Oxides on samples prepassivated in C1 solution contain incorporated C1-and are significantly more resistant to pitting than those formed in C1--free solutions. This increase in pitting resistance for the C1 -treated samples is in contrast to their decreased resistance to open-circuit breakdown. C1-incorporation results in -2% expansion of the NiO lattice leading to a more defective and thus less stable film towards open-circuit breakdown. The ri,d results strongly suggest that C1-incorporated in the oxide lattice (as distinct from C1-in the electrolyte) is not a precursor to pit initiation since it actually increases the resistance to pitting.In a previous paper (1), it was shown that formation of the passive oxide film on nickel in a C1-containing electrolyte resulted in the incorporation of C1-into the oxide lattice. While Auger sputter profiles indicated that the C1-was mainly distributed in the outer layers of the oxide film, the results were not compatible with a simple adsorption of C1-on the oxide surface (cf. 2-7). Indeed, the C1-signal increased substantially as the first oxide layer was sputtered away, and there appeared to be approximately twice as much C1-in the second layer as in the first. The amount of chloride in the film was highly dependent on the [C1-] in solution and the potential of anodization. The maximum homogeneous atomic concentration of C1-which could be achieved was ~-,5%. (This concentration is determined assuming a uniform layer-by-layer distribution of C1-.) The concentration of incorporated C1-quickly reached a steady-state value (~---15s) if the films were formed in a C1-containing solution. On the other hand, incorporation into an initially C1--free NiO film, achieved by subsequent anodization in a C1-containing solution, was dependent on the state of perfection of the passive film. The results suggested that C1-incorporation into an existing passive film occurred via local breakdown-repair events. These breakdown events were not induced by the presence of CI-, but were simply due to chemical dissolution of the oxide at local defects, i.e., the process that gives rise to the corrosion current even in the absence of C1-. Local reformation of the film in the C1-containing solution therefore resulted in a local C1-incorporation. A more perfect oxide film has fewer defects and therefore a slower rate of C1-uptake.While the previous paper (1) indicated that C1-can incorporate into the NiO lat...

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Section: Resultsmentioning

confidence: 99%

Influence of Incorporated Cl− in NiO on the Pitting Susceptibility of Nickel

MacDougall

Graham

1984

J. Electrochem. Soc.

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“…The presence of C1-ions in the solution plays a crucial role in the formation of the unique porous structure produced by reactive deposition. Although CI-may not directly influence the metallic dissolution process, it does interfere with the formation and dissolution of [12,13]. In addition, during deposition in the presence of bubbling oxygen, the cobalt oxide and hydroxide layer may be broken as a result of the sparging effect of the bubbling gas [14].…”

Section: Discussionmentioning

confidence: 99%

Characterization of hydrogen evolution on cobalt electrodeposits in water electrolysis

et al. 1992

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The hydrogen evolution reaction (HER) on cobalt electrodes has been investigated in both alkaline (30wt % KOH) and acid (1 M H2804) media at 25~The electrocatalytic cobalt materials were produced under different electrodeposition conditions, namely deposition in the absence or presence of bubbling oxygen or nitrogen gas with two gas flow rates (80 and 230 ml min-1 ) and at different current densities (50-800Am -2) and deposition in a cobalt powder-containing bath. It has been shown that the electrocatalytic behaviour of the cobalt deposits can be significantly affected by deposition current density via a change of surface area of the cobalt deposits. A considerable HER overpotential decrease (up to 150mV) has been achieved on the highly porous and active cobalt electrodes deposited in the presence of bubbling oxygen and chloride ions in deposition solution. However, the HER overpotential was increased on the cobalt electrodes deposited with bubbling nitrogen in the bath.

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“…It should also be noted that the observations for Cl − interactions with Al reviewed and summarized herein might not be applicable to all metals and alloys. 59,[83][84][85][86][87][88][89][90] …”

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Chloride Ion Interactions with Oxide-Covered Aluminum Leading to Pitting Corrosion: A Review

Natishan

O’Grady

2014

J. Electrochem. Soc.

238

122

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Metals and alloys such as aluminum (Al), stainless steels, and nickel-based alloys exhibit corrosion resistance in a wide range of environments due to the presence of protective, passive oxides. However, in environments that contain aggressive anions such as chloride, Cl − , the passive film becomes unstable and degrades locally causing film breakdown and pitting corrosion. A number of theories describing the initiation of pitting corrosion have been postulated and discussed but to date there is no consensus on the mechanism of breakdown. Since all current mechanisms require Cl − interactions for oxide film breakdown in Cl − containing environments, the question is what is the nature of the interaction of aggressive anions such as Cl − with the passive film, adsorption and/or absorption, leading to pitting? This communication focuses on the interaction of Cl − with the passive oxide film on pure aluminum by reviewing and summarizing the available experimental data concerning Cl − interactions. It should also be noted that the observations for Cl − interactions with Al reviewed and summarized herein might not be applicable to all metals and alloys. Technologically important metals and alloys such as aluminum (Al), stainless steels, and nickel-based alloys exhibit corrosion resistance in a wide range of environments due to the presence of protective, passive oxides.1-90 The passive oxides behave as kinetic barriers, which inhibit further oxidation of the underlying thermodynamically reactive metals. However, in environments that contain aggressive anions such as chloride, Cl − , the passive film becomes unstable and degrades locally causing film breakdown and localized corrosion, which in turn decreases the service life of the materials. The consequence of discrete oxide failure is localized corrosion, which occurs in the forms of crevice corrosion in occluded sites and metastable or stable pitting corrosion on open surfaces. It is generally agreed that localized corrosion occurs in two distinct steps: initiation and propagation.A number of theories describing the initiation of pitting corrosion have been postulated and discussed.

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Effect of Chloride Ion on the Localized Breakdown of Nickel Oxide Films

Cited by 114 publications

References 32 publications

Influence of Incorporated Cl− in NiO on the Pitting Susceptibility of Nickel

Influence of Incorporated Cl− in NiO on the Pitting Susceptibility of Nickel

Characterization of hydrogen evolution on cobalt electrodeposits in water electrolysis

Chloride Ion Interactions with Oxide-Covered Aluminum Leading to Pitting Corrosion: A Review

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