Electrochemical and morphological characterization of porous alumina formed by galvanostatic anodizing in etidronic acid

Iwai, Mana; Kikuchi, Tatsuya; Suzuki, Ryosuke O.; Natsui, Shungo

doi:10.1016/j.electacta.2019.134606

Cited by 17 publications

(6 citation statements)

References 43 publications

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“…19,20 A newly discovered anodizing electrolyte, etidronic acid (1hydroxyethane-1,1-diphosphonic acid, also known as HEDP, C 2 H 8 O 7 P 2 ), can operate at high voltages measuring up to 270 V without burning and breakdown the oxide. [21][22][23][24] Therefore, this unique electrolyte allows the growth of a porous alumina film with a large cell structure and a thick bottom barrier layer during anodizing. Several unique properties, such as a high mechanical hardness, high corrosion resistance, and structural coloration can be achieved from the large-scale porous alumina film formed at high voltages.…”

mentioning

confidence: 99%

Initial Structural Changes of Porous Alumina Film via High-Resolution Microscopy Observations

Iwai¹,

Kikuchi²,

Suzuki³

2020

ECS J. Solid State Sci. Technol.

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The initial growth of a porous alumina film with a large-scale cell structure formed by galvanostatic anodizing in etidronic acid was investigated in detail by high-resolution microscopy. High-purity aluminum plates were galvanostatically anodized in etidronic acid at 2.5–20.0 Am−2. The formation of an anodic oxide and the subsequent instability of the outer oxide simultaneously occurred at the early stage of the linear voltage increase during the anodizing process. Accordingly, a wavy interface boundary between the aluminum oxide that contained incorporated anions and the nearly pure aluminum oxide formed in the anodic oxide. The surviving pores grew as the thickness of the oxide film increased, and a clear porous alumina film with a pore at the center of each cell formed until the voltage reached its maximum value. Finally, steady-state growth of the porous alumina film occurred at the plateau voltage region after a slight voltage decrease. Eggplant-like anion distributions were measured at the head of the pores due to the viscous flow of the anodic oxide. The nanomorphology of the porous alumina film strongly depended on the current density due to the difference in the degree of oxide formation and localized oxide dissolution.

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confidence: 99%

Initial Structural Changes of Porous Alumina Film via High-Resolution Microscopy Observations

Iwai¹,

Kikuchi²,

Suzuki³

2020

ECS J. Solid State Sci. Technol.

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“…The pretreated aluminum specimens were anodized in a 0.3 M etidronic acid solution (TCI, Japan) [31][32][33][43][44][45][46]. A typical simple electrochemical cell was used for anodizing, and a schematic of the apparatus is shown in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

“…However, excessive current densities during anodizing cause the nonuniform growth of porous alumina due to localized current concentrations (oxide burning) [24][25][26][27][28][29]. In particular, anodizing using phosphoric, etidronic, arsenic, citric, and malic acid solutions leads to relatively high voltages; thus, oxide burning is easily induced during anodizing [30][31][32][33][34][35][36]. Hence, a novel anodizing technique must be developed for rapid growth without oxide burning during anodizing at high voltages.…”

Section: Introductionmentioning

confidence: 99%

High-speed galvanostatic anodizing without oxide burning using a nanodimpled aluminum surface for nanoporous alumina fabrication

Iwai

Kikuchi

Suzuki

2021

Applied Surface Science

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“…[1][2][3][4][5] Porous anodic oxide films with a nanoscale honeycomb structure that are less than 1 μm to more than 100 μm in thickness can be easily obtained by anodizing in acidic or alkaline solutions. [6][7][8][9][10][11][12][13][14] Porous oxide films with hydrated oxide are typically used to provide corrosion protection to Al alloys. [15][16][17][18][19] In addition, this characteristic honeycomb nanostructure has been recently used for various nanoapplications, such as nanofilters, nanotemplates, and optical nanodevices.…”

mentioning

confidence: 99%

Formation of Bright White Plasma Electrolytic Oxidation Films with a Uniform Maze-Like Structure by Anodizing Aluminum in Ammonium Tetraborate Solutions

Kikuchi

Sato

Iwai

et al. 2022

J. Electrochem. Soc.

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Bright white plasma electrolytic oxidation (PEO) films with uniform maze-like structures were obtained by anodizing Al in an ammonium tetraborate solution. High-purity Al plates were galvanostatically anodized in 0.3-2.4 M ammonium tetraborate solutions at 303-343 K and 10-100 Am-2. A PEO film consisting of an outer porous layer consisting of amorphous alumina and crystalline alumina with α- and γ-phases and an inner amorphous barrier alumina layer was obtained on the Al surface. An extremely uneven PEO film with various pore sizes and many cracks was formed in a 0.3 M ammonium tetraborate solution, whereas a relatively uniform porous PEO film with similar pore sizes was obtained in 0.9-2.4 M solutions. This difference in the PEO film morphology was due to the plasma generation behavior while anodizing. The lightness of the PEO film increased with increasing anodizing time and PEO film thickness; thus, a bright white PEO film measuring 87.5 in lightness (L*) was formed on the Al surface. The water wettability of the PEO film exhibited weak hydrophilicity. Moreover, a superhydrophobic PEO film with a contact angle of 154° was easily fabricated by self-assembled monolayer modification. Similar bright white PEO coatings were successfully fabricated on various industrial alloys.

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Electrochemical and morphological characterization of porous alumina formed by galvanostatic anodizing in etidronic acid

Cited by 17 publications

References 43 publications

Initial Structural Changes of Porous Alumina Film via High-Resolution Microscopy Observations

Initial Structural Changes of Porous Alumina Film via High-Resolution Microscopy Observations

High-speed galvanostatic anodizing without oxide burning using a nanodimpled aluminum surface for nanoporous alumina fabrication

Formation of Bright White Plasma Electrolytic Oxidation Films with a Uniform Maze-Like Structure by Anodizing Aluminum in Ammonium Tetraborate Solutions

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