The role of electric field in pore formation during aluminum anodization

Oh, Jihun; Thompson, Carl V.

doi:10.1016/j.electacta.2011.02.002

Cited by 195 publications

(181 citation statements)

References 29 publications

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“…However, so far, the distinct three stages of the current oscillation or voltage oscillation have not been elucidated via the field-assisted dissolution and the 'plastic flow' models. [7][8][9][12][13][14][15][16][17][18] For example, the increase of current in Figure 8d and the drop of voltage (decrease of current efficiency) in Figure 8e are both controversial. 18,30 Diggle et al 30 indicated that the mechanism of oxide dissolution is chemical in nature.…”

Section: Resultsmentioning

confidence: 99%

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Chong

Gao

et al. 2015

J. Electrochem. Soc.

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Anodic TiO 2 nanotubes (ATNTs) have been studied extensively for many years. However, their mysterious formation mechanism still remains unclear. The formation of gaps and ribs around the nanotubes has not been elucidated. Here, various surface and cross-section morphologies of ATNTs obtained under different anodizing conditions and their evolution process have been investigated in detail. Based on many experimental facts, new explanations for the gaps and ribs are presented. An entire surface layer covered on the nanotubes plays a primary role on the formation of gaps and ribs. The gaps result from the radial distribution of the electric field at the pore bottom. No newly-formed oxide will exist along the gap direction, because the electric filed along the gap is the minimum. The ribs result from the electrolyte entering into the wider gaps among the ATNTs due to the rupture of the entire surface layer. The rings or ribs on the outer wall of ATNTs are formed at the electrolyte/Ti interface due to the discontinuous existence of a small amount of electrolyte within the gap base. The present viewpoint was demonstrated by an original micro-dam, which can block the electrolyte entering into the gaps and avoid the formation of ribs.

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Section: Resultsmentioning

confidence: 99%

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Chong

Gao

et al. 2015

J. Electrochem. Soc.

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“…13 Oh and Thompson proposed that the mechanical instability in the oxide film accounts for the initial roughening of the oxide film at O/E interface. 3 At valleys of the O/E interface, the electric field is concentrated, which facilitates the pore initiation either by field-assisted dissolution or oxide flow.…”

Section: Introductionmentioning

confidence: 99%

Morphology Defects Guided Pore Initiation during the Formation of Porous Anodic Alumina

Yang

Huang

Lin

et al. 2014

ACS Appl. Mater. Interfaces

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Aluminum (Al) anodization leads to formation of porous structures with a broad spectrum of applications. Naturally or intentionally created defects on Al surfaces can greatly affect pore initiation. However, there is still a lack of systematic understanding on the defect dependent morphology evolution. In this paper, anodization processes on unpolished, polished, and nanoimprinted Al substrates are investigated under high voltages up to 600 V in various acid solutions. A porous structure is obtained on the unpolished and nanoimprinted Al foils with rough surface texture, whereas a compact film can be rationally obtained on the polished Al foil with a highly smooth surface. The observation of surface roughness dependent oxide film morphology evolution could be originated from the high voltages, which increases the threshold requirement of defect size or density for the pore initiation. Electrostatics simulation results indicate that inhomogeneous electric field and its corresponding localized high current induced by the surface roughness facilitate the initiation of nanopores. In addition, the porous films are utilized as templates to produce polydimethylsiloxane nanocone and submicrowire arrays. The nanoarrays with different aspect ratios present tunable wettability with the contact angles ranging from 144.6°to 56.7°, which hold promising potentials in microfluidic devices and self-cleaning coatings.

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“…It is widely used for simulation and structural optimisation of electrolysers with liquid metals, especially for Al reduction [124], cathodic protection systems [125], fuel cells and batteries [126], anodic coatings [127] and other applications. The nonlinearity of EPPs discussed earlier could be a reason why it has not so far been explored for this group of processes.…”

Section: Electromagnetic Field Modellingmentioning

confidence: 99%

Towards smart electrolytic plasma technologies: An overview of methodological approaches to process modelling

Парфенов

Yerokhin

Nev’yantseva

et al. 2015

Surface and Coatings Technology

155

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Article:Parfenov, E.V., Yerokhin, A., Nevyantseva, R. ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Abstract This paper reviews the present understanding of electrolytic plasma processes (EPPs) and approaches to their modelling. Based on the EPP type, characteristics and classification, it presents a generalised phenomenological model as the most appropriate one from the process diagnostics and control point of view. The model describes the system 'power supply -electrolyser -electrode surface' as a system with lumped parameters characterising integral properties of the surface layer and integral parameters of the EPP. The complexity of EPPs does not allow the drawing of a set of differential equations describing the treatment, although a model can be formalised for a particular process as a black box regression. Evaluation of dynamic properties reveals the multiscale nature of electrolytic plasma processes, which can be described by three time constants separated by 2-3 orders of magnitude (minutes, seconds and milliseconds), corresponding to different groups of characteristics in the model. Further developments based on the phenomenological approach and providing deeper insights into EPPs are proposed using frequency response methodology and electromagnetic field modelling. Examples demonstrating the efficiency of the proposed approach are supplied for EPP modelling with static and dynamic neural networks, frequency response evaluations and electromagnetic field calculations.

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The role of electric field in pore formation during aluminum anodization

Cited by 195 publications

References 29 publications

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Morphology Defects Guided Pore Initiation during the Formation of Porous Anodic Alumina

Towards smart electrolytic plasma technologies: An overview of methodological approaches to process modelling

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The role of electric field in pore formation during aluminum anodization

Cited by 195 publications

References 29 publications

Formation Mechanism of Gaps and Ribs Around Anodic TiO2Nanotubes and Method to Avoid Formation of Ribs

Formation Mechanism of Gaps and Ribs Around Anodic TiO2Nanotubes and Method to Avoid Formation of Ribs

Morphology Defects Guided Pore Initiation during the Formation of Porous Anodic Alumina

Towards smart electrolytic plasma technologies: An overview of methodological approaches to process modelling

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Product

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Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs

Formation Mechanism of Gaps and Ribs Around Anodic TiO₂Nanotubes and Method to Avoid Formation of Ribs