Electrodeposition of Iron from Aqueous Solutions Onto an Aluminum Alloy

Abstract

Abstract Heavy metal contaminants such as copper, nickel and cobalt have long been recognized as corrosion hazards in aqueous solutions because their reduction is a comparatively common electrochemical corrosion reaction. It has been known for many years that Fe (III) is corrosive to various metals if the ferric salt is soluble, that is, if the solution is sufficiently acid to maintain the Fe (III) ion in solution. Metals such as aluminum, zinc, cadmium, iron, etc., reduce Fe (III) to Fe (II). Furthermore, if dissolved oxygen is available, more corrosive conditions can result by the oxidation of Fe (II) to soluble Fe (III). Recently a service situation was encountered where ferrous iron in solution was reduced to metallic iron as the result of electrochemical action in an aluminum alloy pipe handling a brine solution. This article describes the laboratory studies conducted to define the mechanism of iron electrodeposition on certain metal alloys from aqueous solutions. Methods to control or prevent such reduction are discussed.