Electrochemical and xps studies of the corrosion behavior of sputter-deposited amorphous W-Zr alloys in 6 and 12 M HCl solutions

Bhattarai, Jagadeesh; Akiyama, Eiji; Habazaki, H.; Kawashima, A.; Asami, K.; Hashimoto, Kôji

doi:10.1016/s0010-938x(97)83351-3

Cited by 41 publications

(26 citation statements)

References 31 publications

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“…In particular, the anodic film thickening is clearly observed in the anodic potential range between 0.2 to 1.0 V (SCE). ox It has been reported that the anodic polarization of W-Ti [22,35], W-Zr [23] and W-Cr [20,36] alloys results in film thickening together with an increase in the ratio of W 6+ ions to the total tungsten ions in the passive film. The same trend is observed in this study on W-xNb alloys by anodic polarization in 12 M HCl.…”

Section: +mentioning

confidence: 96%

“…With increasing molybdenum content in Cr-Ni-Mo alloys showed high anodic current density similarly to molybdenum metal, which suffers transpassive dissolution by anodic polarization owing to the formation of unstable Mo 6+ ions by anodic polarization in 12 M HCl solution [37]. In contrast to Mo 6+ ions, W 6+ ions form a relatively stable film in aggressive hydrochloric acid solutions [20,22,23,28,38]. As a result, anodic polarization of the W-xNb alloys does not lead to an appreciable increase in the anodic current density corresponding to transpassivation of tungsten, although the film thickness increases.…”

Section: +mentioning

confidence: 99%

“…It has been reported that the high corrosion resistance of the sputter-deposited tungsten−based binary [18][19][20][22][23][24][25] and ternary [26,27] alloys in 12 M HCl was based on the formation of new passive double oxyhydroxide films of tetravalent tungsten and alloy-constituting cations. The tetravalent tungsten is the main oxidation state of tungsten for these tungsten-based binary alloys at +0.2 V (SCE) or lower potentials, while the hexavalent tungsten is the main oxidation state of tungsten at +0.4 V (SCE) or higher potentials in hydrochloric acid solutions.…”

Section: Introductionmentioning

confidence: 99%

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X-ray Photoelectron Spectroscopic Study on the Anodic Passivity of Sputter-deposited W-Nb Alloys in 12 M HCl Solution

Bhattarai

2011

J. Sci. Res.

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The effect of a simultaneous additions of tungsten and niobium on the anodic passivity of the surface films of the sputter−deposited amorphous/nanocrystalline W-xNb alloys was studied using corrosion tests, electrochemical measurements and X-ray photoelectron spectroscopic (XPS) analyses. The formation of spontaneous passive film on the alloys, which is composed of double oxyhydroxides of W ox and Nb 5+ ions, is responsible for their higher corrosion resistance than those of the alloy-constituting elements in 12 M HCl solution open to air at 30°C. The quantitative surface analysis by XPS clarifies that the improved anodic passivity of the alloys than those of alloy-constituting elements is based on the formation of new double oxyhydroxide anodic films composed of W 6+ and Nb 5+The passivity of metals or alloys is a subject of significant research in the fields of corrosion science and engineering. The mechanisms of passive film formation and the nature of the passive films can be understood by modern electrochemical theories with the aid of potentiostatic or/and galvanostatic polarization measurements. The change in the current density as a function of polarization potential (that is, deviation of potentials away from equilibrium) represented in the polarization diagrams, and several processes related to corrosion and passivation can be easily understood with the help of the polarization diagrams of the alloys or metals. It must be remembered that experiments have to be performed by controlling the potential and measuring the current (that is, either by ions. These anodic passive films have higher protectiveness and stability than those of the anodic passive oxyhydroxide films of alloy-constituting elements, that is, oxyhydroxides of hexavalent tungsten and pentavalent niobium after potentiostatic polarization for 1 h in 12 M HCl at 30°C.

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Section: +mentioning

confidence: 96%

Section: +mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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X-ray Photoelectron Spectroscopic Study on the Anodic Passivity of Sputter-deposited W-Nb Alloys in 12 M HCl Solution

Bhattarai

2011

J. Sci. Res.

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“…9 Subsequent additions of Zr are not incrementally effective in 12 M HCl; but for 6 M HCl, there is an added reduction in the corrosion rate after addition of ca. 60% Zr.…”

Section: Binary Alloysmentioning

confidence: 99%

Graph Theory and the Passivity of Binary Alloys

McCafferty

2004

J. Electrochem. Soc.

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Graph theory has been employed to model the passivity or corrosion behavior in various electrolytes for the following binary alloys: W-Zr, Al-Zr, Al-Ti, Mn-Ti, Al-Mo, Ti-Zr, Cr-Ti, and Ti-Cr. Sixteen sets of binary alloys have now been modeled using this approach, and the correlation coefficient between the predicted critical alloy composition using the graph theory approach and the experimental alloy composition is 0.932. Conditions under which the graph theory approach is tenable and limitations of the method are also discussed.

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“…It has been reported that the high corrosion resistance of the sputterdeposited binary and ternary tungsten based alloys in 12 M HCl was based on the formation of new passive double oxyhydroxide films of tetravalent tungsten and alloyconstituting cations (Bhattarai 1998(Bhattarai , 2010Bhattarai et al 1995Bhattarai et al , 1997Bhattarai et al b, 1998. The tetravalent tungsten was the main oxidation state of tungsten for these tungstenbased binary alloys at +0.2 V (SCE) or lower potentials, while the hexavalent tungsten is the main oxidation state of tungsten at +0.4 V (SCE) or higher potentials in hydrochloric acid solutions.…”

Section: Introductionmentioning

confidence: 99%

X-ray Photoelectron Spectroscopic Study on the Anodic Passivity of Sputterdeposited W-Ta Alloys in 12 M HCl

Bhattarai

2012

Nepal Journal of Science and Technology

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The role of a simultaneous additions of tungsten and tantalum on the anodic passivity of the passive films of the sputterdeposited nanocrystalline WxTa alloys was studied using immersion tests, electrochemical measurements and Xray photoelectron spectroscopic (XPS) analysis. The formation of spontaneous passive film on the alloys, which is composed of double oxyhydroxide of tungsten and tantalum ions are responsible for their higher corrosion resistance than those of the alloyconstituting elements in 12 M HCl solution open to air at 30C. The quantitative surface analysis by XPS is clarified that the improved anodic passivity of the alloys than those of alloyconstituting elements is based on the formation of new anodic passive oxyhydroxide films composed of W 6+ and Ta 5+ ions. These films have higher protectiveness and stability than those of passive oxyhydroxide films of alloyconstituting elements, that is, oxyhydroxides of hexavalent tungsten and pentavalent tantalum after potentiostatic polarization for 1 h in 12 M HCl.

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Electrochemical and xps studies of the corrosion behavior of sputter-deposited amorphous W-Zr alloys in 6 and 12 M HCl solutions

Cited by 41 publications

References 31 publications

X-ray Photoelectron Spectroscopic Study on the Anodic Passivity of Sputter-deposited W-Nb Alloys in 12 M HCl Solution

X-ray Photoelectron Spectroscopic Study on the Anodic Passivity of Sputter-deposited W-Nb Alloys in 12 M HCl Solution

Graph Theory and the Passivity of Binary Alloys

X-ray Photoelectron Spectroscopic Study on the Anodic Passivity of Sputterdeposited W-Ta Alloys in 12 M HCl

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