Investigation of intrinsic mechanisms of aluminium anodization processes by analyzing the current density

Li, Yi; Ling, Zhiyuan; Hu, Xing; Liu, Yisen; Yi, Chul-Young

doi:10.1039/c2ra01050j

Cited by 90 publications

(48 citation statements)

References 60 publications

(156 reference statements)

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“…2 FE-SEM images (a, d, g), their FFTs (b, e, h) with the intensity profiles (c, f, i) for AAO after the first step of anodization (a-c), concaves on the aluminum surface, formed after oxide removal (d-f) and AAO after the second step of anodization (g-i) formed on high-purity aluminum in 0.3 M sulfuric acid with ethylene glycol as solution modulator Fig. 3 The disordered morphology of AAO after second step of anodization formed on high-purity aluminum at 35 V (top side view) been known that the D c increases with the applied potential [42][43][44]. Likewise anodization current density is made of ionic density (i i ) and electronic current density (i e ).…”

Section: Resultsmentioning

confidence: 99%

“…Likewise anodization current density is made of ionic density (i i ) and electronic current density (i e ). It is commonly accepted that during the anodization process the ionic current density (i i ) can be further divided into oxidation current density (i o ) and incorporation current density (i c ) [42,43]. The addition of EG to electrolyte change the viscosity and as a result decreased i i and i c -this effect concerns to both examinated aluminum foils.…”

Section: Resultsmentioning

confidence: 99%

“…In this research the mixture of sulfuric acid and EG as electrolyte was used, which allows to extend the range of applied anodizing voltage (from 15 V up to 35 V) without burning phenomena occurs. According to intrinsic mechanism the modification of electrolyte by addition of ethylene should leads to decrease of dissociations constant, which leads to higher maximum anodization voltage [42,43] and the better arrangement as consequence. However, above a critical applied anodizing potential, on the aluminum oxide the hillocks and cracks appears resulting in lower quality of AAO matrix [21].…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Characterization of nanopores arrangement of anodic alumina layers synthesized on low-(AA1050) and high-purity aluminum by two-step anodizing in sulfuric acid with addition of ethylene glycol at low temperature

2016

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In this work the anodic aluminum oxide (AAO) was produced by two-step self-organized anodization of two classes purity aluminum in 0.3 M sulfuric acid aqueous solution with addition of ethylene glycol as the solution modifier. The arrangement analysis method based on fast Fourier transforms was applied to characterize the porous arrays ordering. The quality, arrangement, circularity and regularity of nanoporous AAO formed on the low-purity (AA1050) and high-purity aluminum were investigated in details. It was found that the regularity of the nanopores ordering obtained on low-purity aluminum at applied experimental conditions was extraordinarily high while compared to the data published previously. The relation between the structural features of nanopores as well as aluminum concaves ordering obtained in two-step anodization process depending on the step of reaction, was analyzed. It was proven that purity of anodizing aluminum influence the interpore distance, wherein the purer aluminum the smaller interpore distance. The observed phenomenon was discussed in details in accordance with intrinsic mechanism. Furthermore, there are no simple relations between regularity ratio of obtained nanostructures and the step of anodizing.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Characterization of nanopores arrangement of anodic alumina layers synthesized on low-(AA1050) and high-purity aluminum by two-step anodizing in sulfuric acid with addition of ethylene glycol at low temperature

2016

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“…3b and c). The generation of gas voids and aluminum hydroxide has long been considered as the main cause of cell separation effect at HA performed under high current density or voltage conditions [ [25][26][27]. We hereby assumed that the compositions of bright layers are possibly aluminum hydroxide and voids generated by the oxygen evolution during PA process.…”

Section: Sufficient Oxygen Evolution Is Required For Aants Liberationmentioning

confidence: 99%

Rational Design of Ultra-Short Anodic Alumina Nanotubes by Short-Time Pulse Anodization

Wang

Santos

Evdokiou

et al. 2015

Electrochimica Acta

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“…Furthermore, the dissolution equation 2 is acidcatalyzed, however, most of the H + will be driven by the electrical field, gather near the cathode and then released in the form of H 2 gas, as a result, no enough H + takes part in the equation 2 at the pore bottoms. 19,21 Accordingly, the current-time curves of the fourth time anodization in Figure 2c and 3d can hardly be explained via the above discussions. Firstly, the current decreases in the initial stages mean that the oxidation current is unnecessary, because the barrier oxide with enough thickness has been formed both in the second time and the third time anodization.…”

Section: Discussionmentioning

confidence: 82%

Fabrication and Formation Mechanism of Triple-Layered TiO₂Nanotubes

Zhong

Zhang

et al. 2013

J. Electrochem. Soc.

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The formation mechanism of porous anodic TiO 2 nanotubes (PATNT) still remains unclear. A special approach is proposed in this paper to investigate the forming process of nanopores in the preformed nanotubes. A novel and not easily brittle nanostructure, called triple-layered TiO 2 nanotube array, has been fabricated by changing the electrolytes during the electrochemical anodizing processes. The first porous layer was fabricated in fluoride-containing electrolyte, the middle compact layer was formed in fluoridefree electrolyte and the second porous layer was formed in the same fluoride-containing electrolyte. The results show that middle compact layer becomes thicker with the increase of the third time anodizing voltage. At the same time, it needs more time for the fourth time anodization to reach the equilibrium current, where the nanotubes begin to develop steadily. Furthermore, a possible mechanism for the growth of the triple-layered nanotubes is discussed by comparison with the normal PATNT. The present results may be helpful to understand the mechanism of PATNT and facilitate assembling diverse nanostructures for extensive applications in photocatalysis, dye-sensitized solar cells, and biomedical devices.Self-ordering porous anodic alumina (PAA) 1-3 and porous anodic TiO 2 nanotubes (PATNT) 4,5 have been extensively investigated due to their various applications. The formation mechanisms of PAA 6-8 and PATNT 9,10 have received considerable attention. Several models proposed include the field-assisted dissolution (FAD) model, 6,9 the oxide viscous flow model, 8,10,11 oxygen bubble and electronic current model, 7,12,13 etc. For more than 60 years, it has been assumed that fieldassisted dissolution leads to pore formation in PAA, despite a lack of direct experimental evidence that confirms this expectation, 14 because the formation mechanism is hardly derived by in situ experimental methods. 15 In fact, the viscous flow model and anionic incorporation into PAA are both contrary to expectations of the FAD model. 8,11 Moreover, as Hebert et al. indicated that the relationships between porous morphology and the processing parameters (current-time or voltage-time transients) were not yet well understood. 11 It is well known that there are two different types of anodic oxide films for aluminum and titanium, the compact-type film and poroustype film. 16,17 For a constant voltage anodization, the current-time transients of the compact-type and porous-type films are very different. 16,17 Initially both transients are identical; as the initially formed barrier layer thickens, the electric field strength decreases and the current density decreases rapidly. At a special point D p , the two curves now begin to diverge; the compact-type film current continues to decrease exponentially, while the porous-type film current, after a short period of continuing decrease, begins to increase. 16 To the best of our knowledge, most of the researchers assembling the PATNT take fluoride-containing solutions as the anodizing electroly...

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Investigation of intrinsic mechanisms of aluminium anodization processes by analyzing the current density

Cited by 90 publications

References 60 publications

Characterization of nanopores arrangement of anodic alumina layers synthesized on low-(AA1050) and high-purity aluminum by two-step anodizing in sulfuric acid with addition of ethylene glycol at low temperature

Characterization of nanopores arrangement of anodic alumina layers synthesized on low-(AA1050) and high-purity aluminum by two-step anodizing in sulfuric acid with addition of ethylene glycol at low temperature

Rational Design of Ultra-Short Anodic Alumina Nanotubes by Short-Time Pulse Anodization

Fabrication and Formation Mechanism of Triple-Layered TiO₂Nanotubes

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Investigation of intrinsic mechanisms of aluminium anodization processes by analyzing the current density

Cited by 90 publications

References 60 publications

Characterization of nanopores arrangement of anodic alumina layers synthesized on low-(AA1050) and high-purity aluminum by two-step anodizing in sulfuric acid with addition of ethylene glycol at low temperature

Characterization of nanopores arrangement of anodic alumina layers synthesized on low-(AA1050) and high-purity aluminum by two-step anodizing in sulfuric acid with addition of ethylene glycol at low temperature

Rational Design of Ultra-Short Anodic Alumina Nanotubes by Short-Time Pulse Anodization

Fabrication and Formation Mechanism of Triple-Layered TiO2Nanotubes

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Fabrication and Formation Mechanism of Triple-Layered TiO₂Nanotubes