Abstract
The effect of CrO4 2−, MoO4 2− and WO4 2− anions on the inhibition of aluminium corrosion in 0.5 M NaCl solution was investigated. The study comprised potentiodynamic polarization, potentiostatic current–time measurements complemented by SEM–EDAX and XPS investigations. It was found that, the pitting potential of an Al electrode in 0.5 M NaCl solution shifts in the positive direction by addition of CrO4 2−, MoO4 2− and WO4 2− anions, and the shift in potential increases with increase in concentration. A pronounced inhibiting influence was achieved on addition of CrO4 2−, MoO4 2− and WO4 2− anions to the electrolyte during potentiostatic current–time measurements. Chromate anions exhibit a great passivating influence during I/t measurements. This can be explained by the fact that the chromate anion, as a powerful oxidizing agent, is capable of oxidizing the corrosion sites to give a stable Al2O3 film. The inhibition observed on addition of molybdate anions is attributed to the adsorption and reaction of MoO4 2− anions on the electrode surface forming a molybdate layer which selectively impedes the ingress of Cl− ions and hence inhibits the pitting attack. The adsorption of WO4 2− anions at flawed areas and developing pits was found to be the main factor for the observed inhibition.
Similar content being viewed by others
References
M. Pourbaix, ‘Atlas of Electrochemical Equilibria in Aqueous solutions’ (Pergamon, 1966), p. 171.
P.L. Cabot, F.A. Centellas, J.A. Garrido, E. Perez and H. Vidal, Electrochim. Acta 36 (1991) 179.
S.E. Fetes, M.M. Stefenel, C. Mayer and T. Chierche, J. Appl. Electrochem. 20 (1990) 996.
H.S. Srinivasan and C.K. Mital, Electrochim. Acta 39 (1994) 2633.
Z.A. Foroulis and M.J. Thubrikar, J. Electrochem. Soc. 122 (1975) 1296.
Z.A. Foroulis and M.J. Thubrikar, Werkst. Korros. 26 (1975) 350.
S. Dallek and R.T. Foley, J. Electrochem. Soc. 123 (1976) 1775.
T.H. Nguyen and R.T. Foley, J. Electrochem. Soc. 127 (1980) 2563.
B.W. Samuels, K. Sotodudeh and R.T. Foley, Corrosion 27 (1981) 321.
P.M. Natishan, E. McCafferty and G.K. Hubler, J. Electrochem. Soc. 135 (1988) 321.
F. Hunker and H. Bohni, Werkst. Korro. 34 (1983) 68.
B.A. Shaw, G.D. Davis, T.L. Fritz and K.A. Olver, J. Electrochem. Soc. 137 (1990) 359.
M.S. Vukasovich and J.P.G. Farr, Mater. Perform. 25 (1986) 9.
M.S. Vukasovich, Corrosion 89, Paper 444, NACE, Houston, TX (1989).
C. Moniticelli, G. Brunoro, F. Zucchi and F. Fagioli, Werkst. Korros. 40 (1989) 393.
A. Kassab, K.M. Kamel and E. Abd El Hamid, J. Electrochem. Soc. India 36 (1987) 27.
W.A. Badawy and F.M. Al-Kharafi, Corros. Sci. 39 (1997) 681.
C.B. Breslin, G. Treacy and W.M. Carroll, Corros. Sci. 36 (1994) 1143.
A.Kh. Bairamow, S. Zakiour and C. Leygraf, Corros. Sci. 25 (1985) 69.
M.A. Stranick, Corrosion 85, Paper 380, NACE, Houston, TX (1985).
R.C. McCune, R.L. Shilts and S.M. Ferguson, Corros. Sci. 22 (1982) 1049.
K.M. El-Sobki, A.A. Ismail, S. Ashour, A.A. Kheder and L.A. Shalaby, Corros. Prevent. Control 28 (1981) 7.
R.R. Wiggle, V. Hospadaruk and E.A. Styloglou Mater. Perform. 20 (1981) 13.
W.C. Moshier, G.D. Davis and G.O. Cote, J. Electrochem. Soc. 136 (1989) 356.
W.C. Moshier and G.D. Davis, Corrosion 46 (1990) 43.
C.R. Clayton and Y.C. Lu, J. Electrochem. Soc. 133 (1986) 2465.
W.C. Moshier, G.D. Davis, J.S. Aheam and H.F. Hough, J. Electrochem. Soc. 133 (1986) 1063.
C.D. Wagner, W.M. Riggs, L.E. Davis, J.F. Moulder and G.E. Muilenberg (Eds) ‘Handbook of X-ray Photoelectron Spectroscopy’ (Perkin-Elmer Corporation, USA, 1979), p. 51.
T.H. Nguyen and R.T. Foley, J. Electrochem. Soc. 126 (1979) 1855.
L. Tomcsanyi, K. Varga, I. Bartik, G. Haronyi and E. Maleczki, Electrochim. Acta 34 (1989) 855.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Abedin, S.Z.E. Role of chromate, molybdate and tungstate anions on the inhibition of aluminiumin chloride solutions. Journal of Applied Electrochemistry 31, 711–718 (2001). https://doi.org/10.1023/A:1017587911095
Issue Date:
DOI: https://doi.org/10.1023/A:1017587911095