scholarly journals The Corrosion Behavior of Sputter-deposited W-Ti Alloys in 0.5 M NaCl Solution

1970 ◽  
Vol 10 ◽  
pp. 109-113 ◽  
Author(s):  
Jagadeesh Bhattarai

The corrosion behavior of the sputter-deposited amorphous or nanocrystalline W-Ti alloys was studied in neutral 0.5 MNaCl solution at 25°C, open to air by immersion tests, electrochemical measurements and confocal scanning laser microscopic(CSLM) techniques. Titanium metal acts synergistically with tungsten in enhancing the corrosion resistance of the sputter-deposited W-Ti alloys so as to show higher corrosion resistance than those of alloy-constituting elements (that is, tungsten and titanium) in neutral 0.5 M NaCl solution. In particular, the amorphous W-Ti alloys containing 30-53 at% titanium showed lowest corrosion rates (that is, about 1 × 10-3 mm.y-1). Open circuit potentials of all the examined W-Ti alloys were shifted to more noble direction than those of the open circuit potentials of alloyconstituting elements in 0.5 M NaCl solution.Key words: Sputter deposition; W-Ti alloys; Corrosion-resistant; CSLM; NaCl solution.DOI: 10.3126/njst.v10i0.2899Nepal Journal of Science and Technology Volume 10, 2009 December Page:109-113 

1970 ◽  
Vol 23 ◽  
pp. 45-53
Author(s):  
S. P. Sah ◽  
Jagadish Bhattarai

The corrosion behavior of the sputter-deposited amorphous or/and nanocrystalline W-Ni alloys is studied in neutral 0.5 M NaCl solution at 25ºC, open to air using immersion tests, electrochemical measurements and confocal scanning laser microscopic (CSLM) techniques. In general, the corrosion rates of the W-Ni alloys containing less than 20 at% nickel content are slightly lower than that of tungsten metal whereas the corrosion rates of the alloys containing 20 at% nickel or more increased with the addition of nickel in the alloys. The pitting corrosion is observed in the nickel-rich W-69Ni alloy from CSLM studies. The open circuit corrosion potentials of all the examined W-Ni alloys are shifted to noble direction with the addition of nickel content in the alloys.Keywords: W-Ni alloys, passivation, NaCl, electrochemical measurement, pitting.DOI: 10.3126/jncs.v23i0.2096J. Nepal Chem. Soc., Vol. 23, 2008/2009 Page : 45-53


1970 ◽  
Vol 25 ◽  
pp. 53-61
Author(s):  
Minu Basnet ◽  
Jagadeesh Bhattarai

The corrosion behavior of the sputter-deposited nanocrystalline W-Cr alloys wasstudied in 0.5 M NaCl and alkaline 1 M NaOH solutions at 25°C, open to air usingimmersion tests and electrochemical measurements. Chromium metal acts synergisticallywith tungsten in enhancing the corrosion resistance of the sputter-deposited W-Cr alloys soas to show higher corrosion resistance than those of alloy-constituting elements in both 0.5M NaCl and 1 M NaOH solutions. In particular, the nanocrystalline W-Cr alloys containing25-91 at% chromium showed about one order of magnitude lower corrosion rates (that is,about 1-2 × 10-3 mm.y-1) than those of tungsten and chromium metals even for prolongedimmersion in 0.5 M NaCl solution at 25°C. On the other hand, the corrosion rate of thesputter-deposited W-Cr alloys containing 25-75 at % chromium was decreased significantlywith increasing chromium content and showed lowest corrosion rates (that is, 1.5-2.0 × 10-3 mm.y-1) after immersed for prolonged immersion in 1 M NaOH solution. The corrosion ratesof these nanocrystalline W-(25-75)Cr alloys are nearly two orders of magnitude lower thanthat of tungsten and more than one order of magnitude lower corrosion rate than that ofsputter-deposited chromium metal in 1 M NaOH solution. The corrosion-resistant of all theexamined sputter-deposited W-Cr alloys in 0.5 M NaCl solution is higher than in alkaline 1M NaOH solution at 25°C. Open circuit potentials of all the examined W-Cr alloys areshifted to more noble direction with increasing the chromium content in the alloys afterimmersion for 72 h in both 0.5 M NaCl and 1 M NaOH solutions at 25°C, open to air.Keywords: Sputter deposition, nanocrystalline W-Cr alloys, corrosion test, electrochemicalmeasurement, NaCl and NaOH solutions.DOI:  10.3126/jncs.v25i0.3300Journal of Nepal Chemical Society Volume 25, 2010 pp 53-61


1970 ◽  
Vol 22 ◽  
pp. 17-25
Author(s):  
A. Sharmah ◽  
H. Jha ◽  
J. Bhattarai

The passivation behavior of the sputter-deposited amorphous or nanocrystalline W-Ti alloys is studied in alkaline 1 M NaOH solution at 25oC, open to air using corrosion tests, electrochemical measurements and confocal scanning laser microscopic (CSLM) techniques. The corrosion rates of the W-Ti alloys decreased with increasing titanium content and the corrosion rates of the alloys containing 53 at % (atomic percentage) or more titanium as well as the sputter-deposited titanium metal are nearly two orders of magnitude lower than that of the sputter-deposited tungsten in 1 M NaOH solution. The pitting corrosion is clearly observed in the W-Ti alloys containing 30-53 at % titanium from CSLM studies. The open circuit potentials of all the examined W-Ti alloys are located between those of tungsten and titanium metals. DOI: 10.3126/jncs.v22i0.518Journal of Nepal Chemical Society Vol. 22, 2007 pp.17-25


1970 ◽  
Vol 26 (1) ◽  
pp. 17-26
Author(s):  
Jagadeesh Bhattarai

The pitting corrosion of the passive films formed on the surface of sputter-deposited W-30Ti and W-53Ti alloys after immersion for 24 hours in alkaline 1 M NaOH soution at 25°C was studied by using the surface sensitive technique of the confocal scanning laser microscopic (CSLM) technique including corrosion tests and electrochemical measurements. The higher corrosion rate of the W-30Ti alloy (i.e., about 3x 10-2 mm/y) than those of the W-53Ti and W-90Ti alloys (i.e., about 4-5 x 10-3 mm/y) was mostly due to the deep type of pitting corrosion observed on the surface of the passive film formed on the W-30Ti alloy in 1 M NaOH solution. The shallow type of pits was developed on the surface of the passive film formed on the W-53Ti alloy, whereas no pitting corrosion on the titanium-rich W-90Ti alloy.Keywords: Pitting corrosion; Open circuit corrosion potential; Corrosion test; CSLM studyTribhuvan University Journal Vol. XXVI, No. 1, 2009 Page: 17-26


BIBECHANA ◽  
2013 ◽  
Vol 10 ◽  
pp. 1-8
Author(s):  
Susil Baral ◽  
Jagadeesh Bhattarai

The role of tantalum addition on the corrosion behavior of the sputter-deposited nanocrystalline and amorphous W-xTa (x=8-77) alloys was studied in 1 M NaOH solution open to air at 25°C using corrosion tests and electrochemical measurements. Tungsten and tantalum metals act synergistically in enhancing the corrosion resistant properties of the W-xTa alloys and hence addition of 23 at% or more tantalum to the alloys were found to be effective to lower the corrosion rate of the alloys than those of alloy-constituting tungsten and tantalum elements. The corrosion rates of the W-xTa alloys containing 23-77 at% tantalum are nearly two orders of magnitude lower than that of tungsten and even slightly lower than that of tantalum in 1 M NaOH. Addition of tantalum metal in W-xTa alloys is effective for ennoblement of the open circuit corrosion potential of the tungsten metal in 1 M NaOH solution 25°C.DOI: http://dx.doi.org/10.3126/bibechana.v10i0.8363 BIBECHANA 10 (2014) 1-8


1970 ◽  
Vol 22 ◽  
pp. 7-16
Author(s):  
J. Bhattarai ◽  
S. P. Sah ◽  
H. Jha

The passivation behavior of the sputter-deposited amorphous or/and nanocrystalline W-Ni alloys is studied in different concentrations of NaOH solutions at 25°C, open to air using corrosion tests, electrochemical measurements and confocal scanning laser microscopic (CSLM) techniques. The corrosion rates of the W-Ni alloys containing about 60-80 at% nickel are nearly two orders of magnitude lower than that of tungsten and even lower than that of nickel metal in 1 M NaOH solution at 25°C. The pitting corrosion is observed in the tungsten-rich W-9Ni alloy from CSLM studies. The open circuit potentials of all the examined W-Ni alloys are located between those of tungsten and nickel metals in 0.01, 0.1 and 1 M NaOH solutions. The stability of the passive films formed on the sputter-deposited W-Ni alloys increased with decreasing the concentrations of NaOH solutions. DOI: 10.3126/jncs.v22i0.517Journal of Nepal Chemical Society Vol. 22, 2007 pp. 7-16


2013 ◽  
Vol 14 (1) ◽  
pp. 103-108
Author(s):  
Jagadeesh Bhattarai ◽  
Susil Baral

The corrosion behavior of the sputter–deposited amorphous and nanocrystalline W–xTa (x = 8–77) alloys was studied in 0.5 M NaCl solution open to air at 25°C using corrosion tests and electrochemical measurements. Tungsten and tantalum metals act synergistically in enhancing the corrosion resistance of the sputter–deposited W–xTa alloys and hence additions of 23 at. % of tantalum or more to the sputter–deposited W–xTa alloys were found to be effective to achieve significantly high corrosion resistance properties of the alloys than those of alloy– constituting elements. In particular, the corrosion rate of the W–60Ta alloy showed the lowest corrosion rate (that is, 2.0×10-3). The open circuit potential of the alloys shifted noble (positive) direction with immersion time. Addition of tantalum metal in W–xTa alloys is effective for ennoblement of the open circuit corrosion potential of the tungsten metal in 0.5 M NaCl solution open to air at 25°C. Nepal Journal of Science and Technology Vol. 14, No. 1 (2013) 103-108 DOI: http://dx.doi.org/10.3126/njst.v14i1.8929


1970 ◽  
Vol 25 ◽  
pp. 75-82
Author(s):  
Basu Ram Aryal ◽  
Jagadeesh Bhattarai

The synergistic effect of the simultaneous additions of tungsten and zirconium in thesputter-deposited amorphous or nanocrystalline Zr-(12-21)Cr-W alloys is studied in 0.5 MNaCl solution open to air at 25°C using corrosion tests and open circuit potentialmeasurements. Corrosion rates of the sputter-deposited Zr-(12-21)Cr-W alloys containing10-80 at % tungsten (that is, 0.95-1.85 x 10-2 mm.y-1) are more than one order of magnitudelower than that of the sputter-deposited tungsten and even lower than those of zirconium aswell as chromium in 0.5 M NaCl solution. The addition of 8-73 at % zirconium content inthe sputter-deposited binary W-(12-21)Cr alloys seems to be more effective to improve thecorrosion-resistant properties of the sputter-deposited ternary Zr-Cr-W alloys containing12-21 at % chromium in 0.5 M NaCl solution. The sputter-deposited Zr-(17-21)Cr-W alloyscontaining an adequate amounts of zirconium metal showed the more stable passivity andshowed higher corrosion resistance than those of alloy-constituting elements in 0.5 M NaClsolution open to air at 25°C.Keywords: Zr-(12-21)Cr-W alloys, sputter deposition, corrosion test, open circuit potential,0.5 M NaCl.DOI:  10.3126/jncs.v25i0.3305Journal of Nepal Chemical Society Volume 25, 2010 pp 75-82


1970 ◽  
Vol 21 ◽  
pp. 19-25 ◽  
Author(s):  
Jagadeesh Bhattarai

Nanocrystalline, single bcc solid solutions of W-Mo alloys have been successfully prepared by D. C. magnetron sputtering in a wide composition. The corrosion behavior of the sputter-deposited W-Mo alloys was studied. The W-Mo alloys showed significantly high corrosion resistance in 12 M HCl at 30o C. Their corrosion rates are about one and half orders of magnitude lower than that of sputter-deposited tungsten and lower than that of the sputter-deposited molybdenum even after prolonged immersion.DOI: 10.3126/jncs.v21i0.217Journal of Nepal Chemical Society Vol.21 2006 pp.19-25


1970 ◽  
Vol 9 (9) ◽  
pp. 39-43
Author(s):  
Basu Ram Aryal ◽  
Jagadeesh Bhattarai

Simultaneous additions of tungsten, chromium and zirconium in the chromium- and zirconium-enriched sputter-deposited binary W-xCr and W-yZr are effective to improve the corrosion resistance property of the ternary amorphous W- xCr-yZr alloys after immersion for 240 h in 1 M NaOH solution open to air at 25°C. The corrosion rates of all the examined sputter-deposited (10-57)W-(18-42)Cr-(25-73)Zr alloys is higher than those of alloy-constituting elements (that is, tungsten, chromium and zirconium) in aggressive 1 M NaOH solution open to air at 25°C. The corrosion rates of all the examined sputter−deposited W–xCr–yZr alloys containing 10-57 at% tungsten, 18-42 at% chromium and 25-73 at% zirconium were in the range of 1.5-2.5 × 10−3 mm/y or lower which are more than two orders of magnitude lower than that of sputter-deposited tungsten and even about one order of magnitude lower than those of the sputter-deposited zirconium in 1 M NaOH solution. Keywords: Ternary W–Cr–Zr alloys; Amorphous; Corrosion rate; Open circuit potential; 1 M NaOH. DOI: http://dx.doi.org/10.3126/sw.v9i9.5516 SW 2011; 9(9): 39-43


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