Protective Films and Structure Dependent Corrosion in Aluminum

Specimens of high purity aluminum with a high temperature oxide film, or certain others, were compared in 16% HCl with polished and etched specimens. Pitting attack was initiated only at sites where the film had suffered mechanical damage during cooling. The structure-related distribution of these sites, associated with vacancy condensation voids or grain boundary shearing, could determine the distribution of attack overshadowing the intrinsic effects of substrate structure. The pitting parameters were correlated with corrosion kinetics. Previous work in this system was reviewed with regard to possible influences of initial surface condition on the results.