Highly Ordered Anodic Porous Alumina Formation by Self‐Organized Anodizing

Sulka, Grzegorz D.

doi:10.1002/9783527621507.ch1

Cited by 225 publications

(334 citation statements)

References 639 publications

(901 reference statements)

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“…This current-time transient, including the rapid increase, rapid decrease, gradual increase, and steady state, during constant voltage anodizing is typical behavior for the formation of anodic porous alumina on the aluminum surface. The rapid increase and subsequent decrease after the voltage was applied are due to the formation of a thin anodic barrier oxide on the aluminum substrate, the gradual increase is due to the formation of pores in the barrier oxide, and the steady state current density is due to the steady growth of the porous layer [1,2,4]. As the applied voltage increased to 150 V and 160 V, the steady-state current density after the initial transition period increased with the anodizing voltage, 22 Am -2 at 150 V and 29 Am -2 at 160 V. Therefore, the growth rate of the anodic oxide may increase with the anodizing voltage.…”

Section: Resultsmentioning

confidence: 99%

“…Porous alumina fabricated via anodizing has been widely investigated for various basic science and industrial applications such as nanostructure fabrication, electronic/optical devices, and corrosion protection [1][2][3]. The anodizing of aluminum and its alloys under appropriate electrochemical conditions in an appropriate electrolyte solution causes the formation of porous alumina on the aluminum surface [4].…”

Section: Introductionmentioning

confidence: 99%

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Self-ordered Porous Alumina Fabricated via Phosphonic Acid Anodizing

Akiya

Kikuchi

Natsui

et al. 2016

Electrochimica Acta

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Self-ordered periodic porous alumina with an undiscovered cell diameter was fabricated via electrochemical anodizing in a new electrolyte, phosphonic acid (H 3 PO 3 ). High-purity aluminum plates were anodized in phosphonic acid solution under various operating conditions of voltage, temperature, concentration, and anodizing time. Phosphonic acid anodizing at 150-180 V caused the self-ordering behavior of porous alumina, and an ideal honeycomb nanostructure measuring 370-440 nm in cell diameter was successfully fabricated on the aluminum substrate. Conversely, disordered porous alumina grew at below 140 V, and anodizing at above 190 V caused local thickening due to oxide burning. Two-step phosphonic acid anodizing allows the fabrication of high aspect ratio ordered porous alumina. HPO 3 2-anions originated from the electrolyte were incorporated into the porous oxide during anodizing. Consequently, a double-layered porous alumina consisting of a thick outer layer containing incorporated HPO 3 2-anions, and a thin inner layer without anions was constructed via phosphonic acid anodizing.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-ordered Porous Alumina Fabricated via Phosphonic Acid Anodizing

Akiya

Kikuchi

Natsui

et al. 2016

Electrochimica Acta

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“…Most authors observed a decrease of porosity with V for most acids, but, for example, for sulfuric acid, a slight increase was observed, instead (Chu et al, 2005). However, the behavior has been early recognized as a multivariate problem, depending also on several additional operating parameters, such as temperature and anodizing time, and concentration (Sulka, 2008). Additionally, that behavior was observed for pure Al, whereas here we have a different starting metal.…”

Section: Resultsmentioning

confidence: 71%

Advanced Image Analysis of the Surface Pattern Emerging in Ni3Al Intermetallic Alloys on Anodization

et al. 2016

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Anodization of Ni3Al alloy is of interest in the field of industrial manufacturing, thanks to the formation of protective oxide layer on the materials working in corrosive environments and high temperatures. However, homogeneous surface treatment is paramount for technological applications of this material. The anodization conditions have to be set outside the ranges of corrosion and "burning," which is the electric-field-enhanced anodic dissolution of the metal. In order to check against occurrence of these events, proper quantitative means for assessing the surface quality have to be developed and established. We approached this task by advanced analysis of scanning electron microscope images of anodized Ni3Al plates. The anodization was carried out in 0.3M citric acid at two temperatures of 0 and 30°C and at voltages in the range of 2-12 V. Different figures can be used to characterize the quality of the surface, in terms of uniformity. Here, the concept of regularity ratio spread is used for the first time on surfaces of technological interest. Additionally, the Minkowski parameters have been calculated, and their meaning is discussed.

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“…For instance, it has been shown that pore intervals are directly proportional to the anodization voltage of the PAA membranes. [16][17][18] On average, the pore interval increases by 2.5 nm/V, and can be expressed as…”

Section: Quantitative Model Of Barrier Etchingmentioning

confidence: 99%

Etching the Oxide Barrier of Micrometer-Scale Self-Organized Porous Anodic Alumina Membranes

Bellemare

Carignan

Sirois

et al. 2015

J. Electrochem. Soc.

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We develop a quantitative model to calculate the optimal experimental conditions for the etching of the oxide barrier of porous anodic alumina (PAA) membranes. The method is applied to a membrane fabricated at 370 V in a solution of 2% citric acid. The process creates a network of small pores at the bottom of the larger pores, which accelerates the oxide barrier etching relatively to the pore walls of the PAA membranes, when etched in a solution of phosphoric acid. The oxide barrier etching is confirmed by observation of PAA membranes using scanning electron microscopy, revealing the formation of the small pores and the preferential etching of the bottom of the pores rather than the pore walls. The proposed method, which leads to a better control over the fabrication of nanoporous templates, can be adapted to oxide barriers of different PAA membranes formed at different voltages and in different acids. 8 The PAA membranes, which are fabricated by electrochemical processes, exhibit a hexagonal array of vertical pores that are open on their surface and closed by an oxide barrier at the bottom. In order to obtain PAA membranes that are open on both sides, such as required in filter applications or when electrodepositing nanowires, one needs to develop a strategy for removing the oxide on the bottom side.Several articles proposed methods to etch the oxide barrier of PAA membranes, each with their advantages and disadvantages. Han et al. reported a straightforward method to etch the oxide barrier by first removing the PAA membranes from the growth foil, then by covering the open side with a protective polymer made of nitrocellulose and polyester resin, and finally by etching the membrane in phosphoric acid, 5 wt% at 30• C, until the dissolution of the oxide barrier. While this method is relatively simple and applicable to membranes grown at any voltage, that is, with various geometrical parameters, it requires the application of a protective polymer and its subsequent removal, a delicate operation since the membrane is quite fragile. Also, the polymer can contaminate the membrane. This method has been used in our group to fabricate arrays of ferromagnetic nanowires. 10Nielsch et al.11 exploited the natural chemical widening of the pores of PAA membranes in order to decrease the voltage required for anodization due to the oxide barrier being thinner and allowing the formation of smaller pores in the oxide barrier. Their application of a constant current of 0.29 A/cm 2 during 15 min., followed by a constant current of 0.135 A/cm 2 also during 15 minutes, yielded a network of small open pores at the bottom surface. With this interesting insitu method, the oxide layer is not always completely removed, but rather pierced, and it is also difficult to obtain the desired pore size, due to the initial chemical widening. This method was also used with membranes fabricated at 40 V, but no indication about how to extend it to other anodization voltages is provided in the paper.Another approach used by Zhao et al. 12 is to etc...

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Highly Ordered Anodic Porous Alumina Formation by Self‐Organized Anodizing

Cited by 225 publications

References 639 publications

Self-ordered Porous Alumina Fabricated via Phosphonic Acid Anodizing

Self-ordered Porous Alumina Fabricated via Phosphonic Acid Anodizing

Advanced Image Analysis of the Surface Pattern Emerging in Ni3Al Intermetallic Alloys on Anodization

Etching the Oxide Barrier of Micrometer-Scale Self-Organized Porous Anodic Alumina Membranes

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