Mass Transfer and Reaction Rate Analysis on Galvanic Corrosion Behavior of Al–Cu and Al–Sn

Abstract

The galvanic corrosion rate of galvanically coupled Cu–Al and Sn–Al was measured in a 3 wt.% sodium chloride aqueous solution in the previous study. A fundamental mass transfer/reaction model was constructed to analyze a rate controlling step and the effect of dissolved oxygen concentration for galvanic corrosion. It is well known that galvanic corrosion of Al–Cu is diffusion–limited for dissolved oxygen. This behavior can be well explained by the present model. On the other hand, in the case of Sn–Al, it was suggested that the galvanic corrosion rate is a mixed rate controlling of oxygen diffusion and a cathode reaction. The galvanic current depends on the dissolved oxygen concentration in the low oxygen concentration region. And the effect of the reaction rate constant on the galvanic current is large in the high oxygen concentration.