The conditions for incorporation of electrolyte ions into anodic oxides

Leach, Joan; Pearson, B.R.

doi:10.1016/0013-4686(84)87189-3

Cited by 56 publications

(4 citation statements)

References 8 publications

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“…The origin of the initial crack (primary crack) is not entirely clear, but the primary crack could arise from an existing imperfection in the oxide film (3), or from anion incorporation in the oxide (16)(17)(18)(19)(20) dissolution of the oxide film or to stres~s-induced fracture of the oxide film. This small crack or pore provides a path for the solution to reach the oxide/metal interface, so that when the potential is above the pitting potential, metal dissolution and hydrogen production occur at the base of the crack.…”

Section: Resultsmentioning

confidence: 99%

“…Unlike BTA there have been virtually no surface analytical studies of the interaction of TTA with copper. A study of the chemistry of BTA and TTA under typical cooling water conditions revealed a significantly different inhibition behavior of BTA and TTA which was due to the formation of a thinner protective film with more hydrophobic character in the case of TTA (19).…”

Section: Discussionmentioning

confidence: 99%

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The Mechanism of Blister Formation and Rupture in the Pitting of Ion‐Implanted Aluminum

Natishan

McCafferty

1989

J. Electrochem. Soc.

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Optical and scanning electron microscopy of ion-implanted aluminum after polarization above the pitting potential in 0.1M NaC1 have shown that corrosion pits are associated with the formation and rupture of blisters caused by gas evolution. The sequence of events involves: (i) the formation or existence of a primary crack or pore in the oxide film that allows solution contact with the metal, (ii) metal dissolution and hydrogen production at the oxide/metal interface, (iii) formation of a hydrogen pocket (bubble) that stresses the oxide film and causes the nucleation and growth of secondary cracks at the primary crack/pore, (iv) and the eventual rupture of the blister caused by the increasing hydrogen pressure. Griffith-type calculations show that the internal hydrogen pressure required to rupture a typical blister is of the order of 103 atm, whereas thermodynamic data indicate that the internal hydrogen pressure generated within localized corrosion cells on aluminum is about 104 arm.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 147.188.128.74 Downloaded on 2015-06-02 to IP

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Mechanism of Blister Formation and Rupture in the Pitting of Ion‐Implanted Aluminum

Natishan

McCafferty

1989

J. Electrochem. Soc.

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“…During film growth, H + ions are released at the film/electrolyte interface as a product of the film-forming anodic reaction. Consequently, in the absence of buffering by the electrolyte, significant reductions in pH of the electrolyte near to the anodic film surface can occur [48]. Borate ions are highly effective buffers widely used for anodizing valve metals.…”

Section: The Efficiency Of Film Growthmentioning

confidence: 99%

A high-resolution, analytical study of the anodic film formed on GaAs in a tungstate electrolyte

Habazaki

Skeldon

Ghidaoui

et al. 1996

J. Phys. D: Appl. Phys.

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The anodic film formed in aqueous tungstate electrolyte at , to about 295 nm thickness, on -type GaAs at high faradaic efficiency, about 94%, has been examined by analytical transmission electron microscopy, using ultramicrotomed film sections, Rutherford backscattering spectroscopy, x-ray photoelectron spectroscopy, electron probe micro-analysis and scanning electron microscopy. The film is revealed to be amorphous and to comprise a uniform distribution of units of and across the main film thickness, with possible gallium enrichment in the outermost 10 nm or so of the film. Gallium and arsenic are incorporated into the anodic film at the alloy/film interface in the substrate proportions, without development of a layer enriched either in gallium or in arsenic just beneath the anodic film. The formation ratio for the film is about . The film, formed by migration both of cations and of anions across its thickness, is enriched in arsenic relative to the substrate composition, the level of enrichment suggesting that ions migrate outwards in the film about 2.4 times faster than do ions, based on a cation transport number of 0.2. The ions may be ejected, to the electrolyte, under the electric field, on reaching the film/electrolyte interface, with limited formation of an outer layer of essentially at the film/electrolyte interface, or form a layer of , up to about 10% of the total film thickness, which is thinned after anodizing by exposure to the electrolyte and the rinse water. Significantly, the outer layer of film material developed by the faster migrating ions prevents loss of ions from the film during film growth. However, during prolonged exposure to aqueous conditions in the absence of the field, the film becomes enriched in gallium species due to preferential dissolution of arsenic species. The high faradaic efficiency of film growth is a consequence of the presence of a tungsten-enriched layer, probably a gel composed of hydrated tungsten oxide, which develops at the film/electrolyte interface during film growth. No significant presence of tungsten species within the bulk of the anodic film is detected.

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“…However, significant surface acidity can be generated in the electrolyte without pH buffer (15), which may affect the anodic behavior.…”

Section: Introductionmentioning

confidence: 99%

Growth of Anodic Aluminum Oxide Films Without pH-Buffer

Lee¹,

Isaacs

2008

ECS Trans.

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The anodic behavior of abraded pure Al in un-buffered solutions was previously addressed using the cyclic voltammetry and the numerical modeling. In buffer solutions such as borate and phosphate, the Al oxidation current increased rapidly at first and then reached a plateau region, and was analyzed in terms of the high field conduction model and oxide dissolution. However, the anodic current in un-buffered solutions such as sulfate continued to increase with potential. Introducing additional contributions to the earlier model by assuming that the oxide formation efficiency is diminishing with the degree of surface acidity, the features of the anodic behavior in un-buffered solutions, absent in buffered solutions, were simulated.

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The conditions for incorporation of electrolyte ions into anodic oxides

Cited by 56 publications

References 8 publications

The Mechanism of Blister Formation and Rupture in the Pitting of Ion‐Implanted Aluminum

The Mechanism of Blister Formation and Rupture in the Pitting of Ion‐Implanted Aluminum

A high-resolution, analytical study of the anodic film formed on GaAs in a tungstate electrolyte

Growth of Anodic Aluminum Oxide Films Without pH-Buffer

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