Aluminum Alloy Corrosion Inhibition by Vanadates
The inhibition of Al alloy corrosion by vanadates was studied in this work. Vanadium speciation is very complicated and vital to the inhibition efficacy. Critical conditions for decavanadate polymerization from clear metavanadate solutions were investigated. Decavanadate only formed when metavanadate was added to solutions of pH 3 or less. It was not possible to change the pH of a metavanadate solution without forming decavanadates, creating an orange-colored solution. According to ^51 V nuclear magnetic resonance, monovanadates were present only in clear metavanadate solutions; orange solutions always contained decavanadates and never contained monovanadates. Orange decavanadate solutions containing 0.5 M NaCl at pH 8.71 exhibited no significant inhibition of the oxygen reduction reaction and increasing decavanadate concentration was detrimental. In contrast, clear metavanadate solutions containing monovanadate exhibited strong inhibition of the oxygen reduction reaction, to a level similar to chromate. At a fixed pH, increased NaVO3 concentration in clear metavanadate solutions increased inhibition efficiency.
Al alloy corrosion, vanadates, inhibition
Iannuzzi, M.; Young, T.; Frankel, G. S. "Aluminum Alloy Corrosion Inhibition by Vanadates," Journal of the Electrochemical Society, v. 153, no. 12, 2006, pp. B533-B541.