A Study of the Anodic Oxidation of Vanadium

Ellis, B. H.; Hopper, M. A.; Smet, D. J. De

doi:10.1149/1.2408205

Cited by 12 publications

(20 citation statements)

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“…This conclusion is not too unlikely because the sodium tetraborate is dissolved in the water and thus ionized Na2B407 ' I0 H20 ~ 2 Na + + B407--+ i0 H20 [3] The borate ions are then free to move in the electric field. When borate ion reaches the anode it may then yield an oxygen atom to the vanadium, possibly by forming orthoboric acid 12H20+2B4OT--+V~VO2+4e-+BILBO3 [4] This reaction would then result in the formation of an oxide layer on the vanadium. We have investigated the mechanism for the anodization of vanadium.…”

Section: Discussionmentioning

confidence: 99%

“…Fel-xPdx (x ----0.06-0.75) films of 1000A thickness (except as noted) were codeposited on Si or SiO2 substrates held at 275~ (except as noted), using two separate electron-beam-heated Pd (99.993%) and Fe (99.99%) sources in a UHV system (4,5). For a few experiments, films were deposited from a single Fe-Pd * Electrochemical Society Active Member.…”

Section: Methodsmentioning

confidence: 99%

“…To ensure passivity, however, the noble metal concentration must exceed a critical value (3) which is specific to the alloy and corrosive environment. Unfortunately, noble metal additions generally degrade essential magnetic properties (4,5). In our laboratory, we have been attempting to develop novel alloys that have both excellent corrosion resistance and magnetic properties.…”

Section: Oxidation and Corrosion Studies Of Fe -2dx Filmsmentioning

confidence: 99%

“…In order to quantitatively interpret features of the oxidized surface as measured by Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), and ion sputtering techniques, we make use of our earlier sputtering studies of Fel-zPdx films (6). A detailed description of the magnetic and selected atmospheric corrosion properties of these alloys are presented elsewhere (4,5).…”

Section: Oxidation and Corrosion Studies Of Fe -2dx Filmsmentioning

confidence: 99%

“…Ellis et al (4) used an acetic acid solution containing only enough water to dissolve all the sodium tetraborate. Arora and Kelly (5) used a solution 0.02M in sodium tetraborate and 1.0M in water.…”

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confidence: 99%

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The Source of Oxygen in the Anodization of Vanadium

Lewis

Perkins

1979

J. Electrochem. Soc.

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Single crystals of vanadium have been anodized by the method of Keil and Salomon for water soluble oxides. Oxygen-18 enriched water or acetic acid was used in order to trace the oxygen ~rom the acetic acid based solution to the oxide film. The oxygen isotope in the oxide film was determined by the method of nuclear microanalysis utilizing the i60(d,p) and isO(p,~) reactions. The results were compared to those for zirconium anodized in an isO enriched water-based solution. The results showed that, while the zirconium oxide was iso rich, the vanadium oxides were 160 rich. This implies that the anodization mechanism is not the conventional one assumed by Keil and Salomon. Another possible anodization mechanism which could explain the data is discussed.When vanadium is anodized in an aqueous solution, the vanadium oxide film tends to dissolve in the solution as vanadyl ions. Therefore, because of the high solubility of vanadium oxides in water, nonaqueous solutions are necessary to form uniform oxide films on vanadium by anodization. Glacial acetic acid containing small additions of water and sodium tetraborate has been found most suitable for the anodization of vanadium (1-5).Keil and Salomon (1, 2) found that anodization in an acetic acid solution 2.0M in water and 0.02M in NaeB40~ leads to films which are reproducible and characteristic of the formation voltage. The total amount of Na2B407 present in the solution was not considered to be critical; however, the film growth was observed to be sensitive to the water-borate ratio. Breakdown of the oxide film was observed at applied potentials above about 25V.Later studies found that lesser amounts of water in the acetic acid solution would still yield good oxide films. Ellis et al. (4) used an acetic acid solution containing only enough water to dissolve all the sodium tetraborate. Arora and Kelly (5) used a solution 0.02M in sodium tetraborate and 1.0M in water. Therefore, the water-borate ratio may not be as important as previously thought. When the water content was reduced, formation voltages of up to 80 or 90V yielded reproducible films.The oxide film which is formed on vanadium is amorphous (5), and the oxidation state of vanadium in the film is 4.0 [Ref. (2)]. The amorphous structure is retained until the film is heated to about 370~ Keil and Salomon (2) have suggested that the oxygen in the oxide film is provided by the water in the anodizing solution. This was based upon the fact that no oxide film could be formed on the vanadium if water were not present regardless of the voltage or current density applied to the anode. However, the amount of water seems not to be very critical as long as a quantity sufficient to dissolve the sodium tetraborate is present. Other sources of the oxygen may be from the acetic acid itself or from the sodium tetraborate. The source of the oxygen in the film is important in determining the mechanism of formation oI the film. This paper demonstrates a method of determining the source of oxygen in the anodization process. Experiment...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Oxidation and Corrosion Studies Of Fe -2dx Filmsmentioning

confidence: 99%