Postsealing Changes in Porous Aluminum Oxide Films Obtained in Sulfuric Acid Solutions

González, José Antonio Varela; López, V.; Otero, E.; Bautista, A.

doi:10.1149/1.1393301

Cited by 53 publications

(58 citation statements)

References 13 publications

(36 reference statements)

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“…These transformations cause a progressive increase in R p , reflected by a shift of the central section in the Bode diagrams towards higher Z values (Fig. 9, Tables 7 and 8), which, according to the literature, is equivalent to a progressive improvement in anodic film quality [21,22,30]. This type of behaviour, verified in a wide variety of atmospheres for pure Al anodic films [17,24], is thus repeated with Al-Mg and Al-Si-Mg, which present entirely comparable ageing processes.…”

Section: Anodic Film Ageing Processmentioning

confidence: 77%

“…8 gives an instant quantitative perception of this effect, which is similar for all the materials, and of the clear correlation between the porosity of the anodic films (Table 4) and the resistance or "quality" of the porous layers [22,29], which is greater the lower their porosity. The effect of ageing can very probably vary from one alloy to another and distort the close initial relationship between porosity and R p , but in order to verify this it would be necessary to analyse the changes that take place over much longer time periods.…”

Section: Characterisation Of Anodic Films By Eismentioning

confidence: 82%

“…Impedance diagrams were also determined at the end of the three aforementioned exposure times -6, 12 and 24 monthsnoting a progressive increase in the R p with ageing, which according to the literature reveals a progressive improving of the anodic films quality [22,29]. In Tables 7 and 8, are compared the R p , C p and C b values of recently sealed anodic films and after one year of exposure to the atmosphere, respectively.…”

Section: Characterisation Of Anodic Films By Eismentioning

confidence: 93%

“…As it happened in the case of commercial purity aluminium [11,17,[21][22][23], the final stage in the complex sealing mechanism, ageing, continues for months and years and finally comes to plug the entire pore length with trihydrated alumina Al 2 O 3 ·3H 2 O-Al(OH) 3 -. These transformations cause a progressive increase in R p , reflected by a shift of the central section in the Bode diagrams towards higher Z values (Fig.…”

Section: Anodic Film Ageing Processmentioning

confidence: 99%

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Behaviour of different bare and anodised aluminium alloys in the atmosphere

Bartolomé

Río²,

Escudero

et al. 2008

Surface and Coatings Technology

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Exposure tests in natural atmospheres are an indispensable means for determining the behaviour and durability of metallic materials in the atmosphere. The corrosion behaviour of bare aluminium and anodised aluminium with three different coating thicknesses has been evaluated for two years' exposure in two natural atmospheres of very different corrosivities: one urban and the other marine. Several techniques have been used to evaluate changes in the specimens during exposure, but special attention is paid to the direct measurement of corrosion by gravimetry and its indirect estimation by the comparatively much more sensitive electrochemical impedance spectroscopy (EIS) technique. The results show that if no demands are placed on the conservation of its appearance, aluminium may be used without protection even in atmospheres of medium or high corrosivity. The anodising and sealing of aluminium alloys, above an ill-defined minimum thickness threshold, is an appropriate solution to prevent localised corrosion of aluminium and to conserve its appearance, even in aggressive atmospheres.

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Section: Anodic Film Ageing Processmentioning

confidence: 77%

Section: Characterisation Of Anodic Films By Eismentioning

confidence: 82%

Section: Characterisation Of Anodic Films By Eismentioning

confidence: 93%

Section: Anodic Film Ageing Processmentioning

confidence: 99%

See 2 more Smart Citations

Behaviour of different bare and anodised aluminium alloys in the atmosphere

Bartolomé

Río²,

Escudero

et al. 2008

Surface and Coatings Technology

Self Cite

View full text Add to dashboard Cite

show abstract

“…When these coatings are studied in the transmission electron microscope, the oxide is rapidly transformed due to the effect of the electron beam, which is attributed to drying, ageing and, for long times, crystallisation processes [9][10][11] .…”

Section: Palabras Clavementioning

confidence: 99%

Contribution of electron microscopy to the study of sealing processes in oxalic anodised aluminium

Bartolomé¹,

López²,

Escudero³

et al. 2007

Rev. metal.

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Transmission electron microscopy (TEM) of anodic coatings reveals a substructure in which three regions are clearly differentiated: a very thin band at the hexagonal cell boundaries; the cell walls contaminated with anions from the anodising bath; and the hydrated alumina that fills the pores with a certain amount of retained water. Scanning electron microscopy (SEM) appears to be a highly suitable tool to observe, at the surface and at more internal levels, the structural changes associated with each sealing degree. Both types of electron microscopy allow the possibility to visualise the different stages of the very complex sealing and ageing mechanisms indirectly determined by gravimetric and electrochemical techniques. KeywordsOxalic anodised aluminium. Sealing. Electron microscopy.Contribución de la microscopía electrónica al estudio de los procesos de sellado en el aluminio anodizado en ácido oxálico

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Oil‐Impregnated Nanoporous Oxide Layer for Corrosion Protection with Self‐Healing

Lee

Shin

Jiang

et al. 2017

Adv Funct Materials

111

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The major drawback of current passivation techniques for preventing corrosion is the lack of ability to withstand any external damages or local defects. In this study, oil‐impregnated nanoporous anodic aluminum oxide (AAO) layers are investigated to overcome such limitations and thus advance corrosion protection. By completely filling hydrophobized nanopores with oil via a solvent exchange method, a highly water‐repellent surface that prevents the penetration of corrosive media into the AAO layer and hence the corrosion of aluminum is achieved. The impregnation of oil into the hydrophobic nanoporous AAO layer enhances the corrosion resistance of an AAO layer by two and four orders of magnitude compared to that of a hydrophobic (i.e., air‐entrained) and a bare (hydrophilic) AAO, respectively. In the presence of local defects, the oil impregnated within the hydrophobic nanoporous AAO layer naturally permeates into the defects and ultimately inhibits the exposure of the aluminum surface to corrosive media. Whereas the corrosion current density of the air‐entrained hydrophobic AAO layer increases by more than 30 times after cracks, that of the oil‐impregnated AAO layer increases by no more than 4 times, showing superior anticorrosion property even after there are cracks, owing to the effective self‐healing capability.

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Postsealing Changes in Porous Aluminum Oxide Films Obtained in Sulfuric Acid Solutions

Cited by 53 publications

References 13 publications

Behaviour of different bare and anodised aluminium alloys in the atmosphere

Behaviour of different bare and anodised aluminium alloys in the atmosphere

Contribution of electron microscopy to the study of sealing processes in oxalic anodised aluminium

Oil‐Impregnated Nanoporous Oxide Layer for Corrosion Protection with Self‐Healing

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