The anodic oxidation of valve metals—I. Determination of ionic transport numbers by α-spectrometry

Khalil, N.; Leach, Joan

doi:10.1016/0013-4686(86)80148-7

Cited by 135 publications

(58 citation statements)

References 12 publications

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“…Since silicon species are immobile during growth of various anodic oxides, including anodic aluminium oxide [30], niobium oxide [31], tantalum oxide [18,19]and titanium oxide [23,24], the transport number of cations, t + , can be determined from the ratio of the number of cations in the outer silicon-free layer to the total number of cations in the anodic film, giving 0.42. The value is consistent with the previously determined values [23,32].…”

Section: Introductionsupporting

confidence: 82%

Fast migration of fluoride ions in growing anodic titanium oxide

Habazaki

Fushimi

Shimizu

et al. 2007

Electrochemistry Communications

168

110

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Section: Introductionsupporting

confidence: 82%

Fast migration of fluoride ions in growing anodic titanium oxide

Habazaki

Fushimi

Shimizu

et al. 2007

Electrochemistry Communications

168

110

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“…to allow them to completely selforganize), this variation shows that the grain structure slightly influences also the nanotube diameter. It is known from literature, that the thickness of anodic TiO2 films is directly proportional to the applied voltage [1][2][3][4][5][6]. The same rule also applies for the nanotube diameter vs. voltage used for the nanotube growth [9,22,23].…”

Section: Resultsmentioning

confidence: 82%

Influence of the Ti microstructure on anodic self-organized TiO2 nanotube layers produced in ethylene glycol electrolytes

Macák

Jarošová

Jäger

et al. 2016

Applied Surface Science

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The relationship between the microstructure of Ti substrates and the anodic growth of selforganized TiO2 nanotube layers obtained upon their anodization in the ethylene glycol based electrolytes on these substrates is reported for the first time. Polished Ti sheets with mirror-like surface as well as unpolished Ti foils were considered in this work. Grains with a wide range of crystallographic orientations and sizes were revealed by Electron Backscatter Diffraction (EBSD) and correlated with nanotube growth on both types of substrates. A preferred grain orientation with (0001) axis perpendicular to the surface was observed on all substrates. Surfaces of all substrates were anodized for 18 hours in ethylene glycol electrolytes containing 88 mM NH4F and 1.5% water and thoroughly inspected by SEM. By a precise comparison of Ti substrates before and after anodization, the uniformity of produced self-organized TiO2 nanotube layers was evaluated in regard to the specific orientation of individual grains. Grains with (0001) axis perpendicular to the surface turned out to be the most growth-promoting orientation on polished substrates. No orientation was found to be strictly growth-retarding, but sufficient This postprint version is available from http://hdl.handle.net/10195/61977 Publisher's version is available from http://www.sciencedirect.com/science/article/pii/S0169433216304482 DOI: 10.1016DOI: 10. /j.apsusc.2016 This document is licenced under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0.International. ______________________________________________________________________________________________________ 2 anodization time (24 hours) was needed to obtain uniform nanotube layers on all grains without remnant porous initial oxide. In contrast with polished Ti sheets, no specific orientation was found to significantly promote or retard the nanotube growth in the case of unpolished Ti foils.Finally, the difference between the average nanotube diameters of nanotubes grown on various grains was investigated showing non-negligible differences in the diameter for different grain orientations and substrates.

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“…[22][23][24] The outer 35-38% of the film is formed at the film/electrolyte interface through the egress of Ti 4+ ions, with the remaining film formed at the metal film interface by the ingress of O 2 /OH − ions. 24 The electrolyte-derived species are mainly incor-porated into the outer layer of the anodic films and may stabilize the amorphous structure. 25 The traditional anodizing technique employed a lab DC power supply to apply a constant voltage/current directly, and the anodizing is processed for a period of time.…”

mentioning

confidence: 99%

Anodic Film Growth of Titanium Oxide Using the 3-Electrode Electrochemical Technique: Effects of Oxygen Evolution and Morphological Characterizations

Liu

Zhong

Walton

et al. 2015

J. Electrochem. Soc.

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In the present study, potentiodynamic polarization scans followed by potentiostat anodizing tests have been employed to generate the anodic oxide films on commercially pure Ti in 1 M sulfuric acid and 1 M phosphoric acid. The highly stable single-barrier anodic films with a growth ratio of ∼1.5 nm V −1 (sulfuric acid) or ∼1.7 nm V −1 (phosphoric acid) were generated at the anodic voltages from 10 V to 60 V. During the potentiostatic anodizing, the anodic film was formed after the growth of the passive oxide film in the potentiodynamic polarization stage. Oxygen evolution proceeded within both the polarization and the anodizing stages, resulting in the suppression of the current efficiency for the growth of anodic films. The oxygen bubbles were induced by the amorphous-to-crystalline transition within the anodic film, leading to the formation of blister textures. Significant rupture of the anodic film was found that started at 20 V of the anodizing processes in the sulfuric acid; conversely, the significant rupture was started at 50 V in the phosphoric acid. The XRD results indicated that the degree of amorphous-to-crystalline transition in the anodic film formed in the phosphoric acid was less than the film formed in the sulfuric acid. The phosphate titanium oxide layers detected by XPS in the phosphoric acid indicated that more degrees of the amorphous-to-crystalline transition might be inhibited compared with the sulfated titanium oxides found in the sulfuric acid. Titanium can be anodized in acidic and basic solutions under potentiostatic or galvanostatic conditions. In view of the variation of titanium anodizing conditions, it is possible to tailor the anodic film thickness formed on the surface of titanium.1 The coloration of the oxide film produced through anodic oxidation is indicative of the thickness. This relation between color and thickness of the oxide is dependent on the anodizing condition and the nature of the electrolyte. Further, the thickness of the anodic oxide layer has been shown to be a linear function of the applied voltage.2-5 The anodic oxide film on titanium is basically amorphous in crystal structure and morphologically homogeneous.6 Moreover, such an oxide layer provides excellent resistance to corrosion as indicated electrochemically by a low level of electronic conductivity, 7 thermodynamically great stability 8 and low ion-formation tendency in aqueous environments. 9 The growth of the oxide thickness results in systemic changes of the surface topography, particularly in the surface pore configuration, 10 whereas electrolyte derived anion incorporation into oxide films will modify the chemical composition as well as the crystal structure. [11][12][13] It is generally known that titanium behaves as a typical valve metal for which oxide growth involves field-assisted migration of ions through the films and for the thickness to follow Faraday's law. [14][15][16] Further, the growth constant values of the anodic film are variable according to many academics. 17,18 It is reported that a...

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The anodic oxidation of valve metals—I. Determination of ionic transport numbers by α-spectrometry

Cited by 135 publications

References 12 publications

Fast migration of fluoride ions in growing anodic titanium oxide

Fast migration of fluoride ions in growing anodic titanium oxide

Influence of the Ti microstructure on anodic self-organized TiO2 nanotube layers produced in ethylene glycol electrolytes

Anodic Film Growth of Titanium Oxide Using the 3-Electrode Electrochemical Technique: Effects of Oxygen Evolution and Morphological Characterizations

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