Effect of chromate concentration on the repassivation of corroding aluminum

摘要

Current density maps of anodically polarized pure aluminum in chloride solutions211u001ewere measured and the effect of chromate/dichromate buffer additions monitored. 211u001eThe higher the polarized potential the more chromate was required to repassivate 211u001ethe corroding surface. Small pits repassivated easily, crevice corrosion events 211u001ewere the last to repassivate. Open circuit potential measurements showed the 211u001epresence of meta-stable pitting at chloride concentrations of 0.3M. The lifetime 211u001eand magnitude of these metastable pits was reduced on the addition of 0.05M 211u001echromate buffer.