Untersuchungen uber die anodische auflösung und die lochfraβkorrosion von nickel-einkristallelektroden

Garz, I.; Worch, H.; Schatt, W.

doi:10.1016/s0010-938x(69)80045-4

Cited by 34 publications

(8 citation statements)

References 16 publications

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“…These samples exhibited Laue x -r a y diffraction patterns which suggested a mosaic subgrain strUcture. Whereas Garz et al (12) reported observing rectangular pits on {110} regularly, in the present work only the "anomalous" grystals exhibited pits of this shape.…”

Section: Morphology Of Corrosion Pits On Nickelcontrasting

confidence: 68%

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Aggressive Ion Accessibility and the Morphology of Corrosion Pits

Tokuda¹,

Ives²

1971

J. Electrochem. Soc.

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Corrosion pits were formed under potentiostatic conditions on {100}, {111}, and {110} surfaces of nickel in 1N H2SO4 normalor false(0.5N NiSO4+0.01N H2SO4false) solution by adding Cl− ions at passive potentials. The morphologies of the pits obtained were analyzed using a model based on the atomistic mechanics of dissolution. It is found that a simulation, which removed atoms one by one according to the principle that atoms more accessible to the aggressive ions are removed more easily, approximates the morphologies of pits obtained experimentally. Observed morphological changes with the reaction rate (dependent on the degree of passivation, the potential of chloride addition and the acidity of the solution) could also be accounted for by appropriate modification of the simulation procedure. The simulation also is shown to predict the morphology of corrosion pits in body‐centered cubic metals reported by other workers. It is proposed that the state of close‐packing of a crystal surface is not the only factor to be considered in determining the relative dissolution rates of crystallographic surfaces when aggressive ions are present.

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Section: Morphology Of Corrosion Pits On Nickelcontrasting

confidence: 68%

“…Garz et al (12) have studied the morphology of corrosion pits formed in 0.5N NiC12 on {111}, {100), and {110} surfaces of nickel. They state that faces of high atomic density constitute the facets of pits obtained at high anodic potentials.…”

Section: Morphology Of Corrosion Pits On Nickelmentioning

confidence: 99%

Aggressive Ion Accessibility and the Morphology of Corrosion Pits

Tokuda¹,

Ives²

1971

J. Electrochem. Soc.

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“…2a). The pit density was ~ 102 cm -2, about four orders of magnitude less than the measured dislocation density for this specimen, indicating that only a fraction of the existing dislocations were revealed during dissolution under these experimental conditions (16)(17)(18). In this experiment a liquid nitrogen trap was used in order to prevent appreciable backstreaming of oil vapor from the vacuum pump to the cell, during repeated evacuation and hydrogen flushing, before the introduction of solution into the cell.…”

Section: Resultsmentioning

confidence: 84%

The Morphological Changes of Low Index Planes of Copper Single-Crystal Electrodes near Equilibrium

Markovac¹

1972

J. Electrochem. Soc.

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These relationships agree reasonably well with the experimental results (Eq.[10] to [13]).As shown in Fig. 1, the abrupt change in the polarization of iron in low concentrations of chloride ions at the higher potentials suggest a change in the dissolution mechanism. It should be noted that at these higher potentials the dissolution rates are sufficiently large that the measured potential must be corrected for the IR potential drop. It is surmised that two dissolution mechanisms occur simultaneously. One involves the direct participation of the chloride ions in the dissolution of iron, and the second is independent of chloride ions. At low polarization the former mechanism is dominant, but at higher polarization a dissolution mechanism such as the one proposed by Bockris (17) maybe dominant. ABSTRACTThe behavior of low index planes of copper single-crystal electrodes, simultaneously exposed to deaerated and pre-equilibrated acidic copper sulfate solution, has been studied. The surface topographies indicated that a small net dissolution reaction occurred, due to traces of oxygen present in the experimental system, in spite of all the purification steps applied. Potential differences between electrodes were within 1 mV. A low rate dissolution reaction occurred everywhere on the exposed surfaces of all specimens, but the extent of dissolution varied over the surface of the same specimen, indicating considerable heterogeneity of the metal crystal surfaces. The surface features formed during dissolution on all electrodes, like grooves, pyramidal pits, macro ledges, hillocks, etc., are consistently bounded by the {210}, {111}, and {100} planes. The application of Batterman's stability conditions indicates that these planes are slow dissolving and stable, under present experimental conditions. The crystallographic characteristics of these planes, in relation to the process of dissolution, are discussed. Mechanisms of formation of these surface features are proposed utilizing the terrace-ledge-kink model for metal crystal dissolution, and considering the effects of crystallographic structure, surface imperfections, and adsorbed inhibiting species on the step motion over the surface, for the given rate of dissolution.

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“…From eqs. (10) and (12), (13) and hence (14) From our experiments we estimate the current density i0 at the pit mouth. From eqs.…”

Section: Pitting Dissolution Currentmentioning

confidence: 99%

“…If we assume that the mass transfer of metal ion across the pit mouth is controlled mainly by the diffusion, k in (14) we obtain…”

Section: It Is Remarkablementioning

confidence: 99%

Generation and Propagation of Chloride-Pits on Rotating Stainless Steel Electrode in Acid Solution

et al. 1972

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Anodic pit generation and pit growth of stainless steel at constant potential in a sulphuric acid solutlutturic acid solutphuric acid solutttd soluttution containing chloride ion have been investigated by use of a rotating electrode. The electrode rotation makes the generation and growth of pits very stable and enables the pit generation frequency and the pitting current from a single pit to be measured potentiostatically. The pits break out at constant frequency and the rate of pit generation is a linear function of the potential, suggesting that the pit generation proceeds electromechanically rather than electrochemically. An incubation time, probably associated with the initial adsorption of chloride ion, is found before the linear pit generation commences, which differs from the induction time for opening an initial pit.The pitting current is in proportion to the area of pit mouth with the current density (8A/cm2) which is independent of the potential, indicating that the mass transfer is rate-limiting. The pit grows following a parabolic law and the rate constant is an exponential function of the potential, from which a pit model is proposed in which the transpassive film continuously forming and breaking down on the inner pit surface assumes a high electric field.

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Untersuchungen uber die anodische auflösung und die lochfraβkorrosion von nickel-einkristallelektroden

Cited by 34 publications

References 16 publications

Aggressive Ion Accessibility and the Morphology of Corrosion Pits

Aggressive Ion Accessibility and the Morphology of Corrosion Pits

The Morphological Changes of Low Index Planes of Copper Single-Crystal Electrodes near Equilibrium

Generation and Propagation of Chloride-Pits on Rotating Stainless Steel Electrode in Acid Solution

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