Influence of Casting Temperature on Electrochemical Behavior of Al-Zn-In Sacrificial Anodes

Document Type : Research Article


Metallurgy and Materials Department, Faculty of Engineering, University of Tehran, P. O. Box 11365/4563, Tehran, I. R. IRAN


Aluminum anodes have been widely used in the cathodic protection of marine structures. However there are conditions in which these anodes become passivated or face some localized or unwanted corrosion, which influences their efficiency. Addition of alloying elements such as Zn and In not only have improved the efficiency of the anodes but also the effect of casting parameters such as ultra melt temperature Tm , mold temperature and grain refiners can adversely influence the capacity of aluminum anodes. In this work the effects of ultra melt temperature and mold temperature have been studied on the potential and current capacity of Al-Zn-In anodes. Electrochemical polarization and NACE standard methods were used to evaluate the anodic behavior, potential and current capacity of the anodes. It is shown that metallic molds having higher temperatures could provide better condition for obtaining homogenous structures with minor inclusions. The optimum condition of anode operation may be provided where mold and pouring temperatures equal to 400 ºC and 710 ºC respectively, in which a fine structure, phase distribution and lack of casting faults are obtained. The microstructures that can provide a homogenous anodic dissolution bring by itself optimum efficiency of the anodes.


Main Subjects

[1] Daloz, D., Steinmets, P., Corrosion Behavior of Rapidly Solidified Magnesium Aluminum-Zinc Alloys, Corrosion, 53, p. 944 (1997).
[2] Aragon,  E.,  Cazenave-Vergez, L., Sebaound, A., Electrochemical Behaviour of Binary Al-Ga and Ternary Al-Zn-Ga Alloys as Function of Thermo-dynamic, British Corrosion Journal, 32, p. 121 (1997).
[3] Kulkarni, A. G., Gurrappa, I., Effect of Magnesium Addition on Surface Free Energy and Anode Capacity of Indium Activated Aluminium Alloys, British Corrosion Journal, 28, p. 67 (1993).
[4] Carroll, W. M., Breslin, C. B., Activation of Alu-minum in Cloride Solutions Contining Activator Ions, Corrosion Science, 33 (7), p. 1161 (1992).
[5] El Shayeb, H. A., Abd El Wahab, F. M., Zein El Abedin, S., Electrochemical Behaviour of Al, Al-Sn, Al-Zn and Al-Zn-Sn Alloys in Chloride Solutions Containing Stannous Ions, Corrosion Science, 43, p. 655 (2001).
[6] Munoz, A. G., Bessone, J. B., Effect of Different Anions on the Electrochemical Behavior of In, Electrochim. Acta, 43 (9), p. 1067 (1998). 
[7] Munoz, A. G., Saidman, S. B.,  Bessone,  J. B., Corrosion of an Al-Zn-In Alloy in Chloride Media, Corrosion Science, 44, p. 2171 (2002).
[8] Venugopal, A., Raja, V. S., Ac Impedance Study of the Activation Mechanism of Aluminum by Indium and Zinc in 3.5% NaCl Medium, Corrosion Science, 39, p. 2053 (1997).
[9] Munoz, A. G., Bessone, J. B., Cathodic Behavior of In in Aqueous Sodium Cloride Solutions, Electro-chim. Acta, 43 (14), p. 2033 (1998).
[10] Bresiln, C.B., Friery, L.P., The Synergistic Interaction between Indium and Zinc in the Activation of Aluminum in Aqueous Electrolytes, Corrosion Science, 36 (2), p.231 (1994).
[11] Srivastava,  S. C., Ives,  M. B., Dissolution of Inclu-sions in Low-Alloy Steel Exposed to Chloride-Containing Environments, Corrosion, 43, p. 687 (1987).
[12] Reboul,  M. C., Gimenez,  P. H., Rameau, J. J., Proposed Activation Mechanism for Al Anodes, Corrosion, 40, p. 366 (1984).
[13] Venugopal, A., Raja, V. S., Evidence of Dissolution Redeposition Mechanism in Activation of Aluminum by Indium, British Corr. Journal, 31 (4), p. 318 (1996).
[14] Venogupal, A., Sram, V., Evidence of Dissolution-Redeposition Mechanism in Activation of Alu-minium by Indium, British Corrosion Journal, 31, p. 46 (1996).
[15] Bresslin, C. B., Carrol, W. M., The Effect of Indium Precipitation on the Electrochemical Divalution of Al-In Alloys, Corrosion Science, 34 (7), p. 1099 (1993).
[16] Faghalyi,  K., Scartleburg, D.,  Adverse  Effect of Temperature on the Operating-Potential Behavior of Al-Zn-In alloys, Journal of Applied Electro-chemistry, 32, p. 410 (2002).
[17] Barbucci, A., Cerisola, G., Bruzzone, G., Saccone, A., Activation of Aluminium Anodes by the Presence of Intermetallic Compounds, Electrochemical Acta, 42, p. 2369 (1997).
[18] Salinas, D. R., Bessone, J. B., Munoz, A.G., Electro-chemical Behaviour of Al-5%Zn-0.1%Sn Sacrificial Anode in Aggressive Media: Influence of Its Alloying Elements and the Solidification Structure, Corrosion Science, 32, p. 665 (1991).
[19] Lin,  J., Shih,  H., Improvement  of  the  Current Efficiency of Al-Zn-In Heat Anode by Treatment, Electrochemical Science and Technology, 134, p. 817 (1987).
[20] NACE  Standard,  TM0190-98,  “Standard  Test Method Impressed Current Laboratory Testing of Aluminum Alloy Anodes”, pp. 3-8 (1998).
[21] Bresslin, C. B., Carrol, W. M., The Effect of Indium Precipitation on the Electrochemical Divalution of Al-In Alloys, Corrosion Science, 34 (7), p. 1099 (1993).
[22] Bessone,  J. B., Suarez Baldo,  R. A.,  Sea  Water Testing of Al-Zn-Sn and Al-Zn-In Sacrificial Anodes, Corrosion Science, , 88, p. 453 (1981).
[23] Morgan, J. H., “Cathodic Protection”, 2nd ed., Texas, National Association of Corrosion Engineers (NACE), pp. 113-144 (1993).
[24] Shreir, L. L., Corrosion Control of Steel, Corrosion, 2, p. 11 (1978).