This is a relatively old article; in fact, this is my first peer reviewed paper. Of all the publications that derived from my Ph.D. dissertation, “Aluminum alloy corrosion inhibition by vanadates” is, by far, the most important one. Curiously, from the series of articles on vanadates, it is not the most cited one, it should have been.

Why is it important?

Together with my colleague Dr. Tanya Young and my academic adviser, Prof. Jerry Frankel, we solved the puzzle of vanadate speciation in aqueous solutions and its influence on the corrosion inhibition of aluminum alloys. This article challenged the contemporary understanding of the vanadate system, marking an inflection point on aluminum alloy corrosion inhibition research.

Using nuclear magnetic resonance spectroscopy and electrochemical techniques, we discovered that while metavanadates were as efficient as chromates in inhibiting localized corrosion of the aluminum alloy AA2024-T3 (UNS A92024), decavanadates were detrimental. Indeed, metavanadates had a dramatic effect on the kinetics of the oxygen reduction reaction, making them one of the most potent cathodic inhibitors of aluminum alloy corrosion.

Abstract

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 \(\text{NaVO}_3\) concentration in clear metavanadate solutions increased inhibition efficiency.

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Citation

Iannuzzi, M., Young, T. & Frankel, G. S. “Aluminum Alloy Corrosion Inhibition by Vanadates.” J. Electrochem. Soc. 153, B533, doi:10.1149/1.2358843 (2006).