The effect of strontium and chromate ions on the inhibition of zinc

The corrosion and inhibition of zinc in artificial acid rain solution (pH 4.5) at a low strontium chromate concentration has been evaluated using electrochemistry, solution analysis and XPS. These techniques have been used to estimate inhibitor efficiency and to determine a possible inhibition mechanism. The results show that strontium chromate at low concentration inhibited significantly more of the cathodic corrosion process, by reduction of Cr6+ to a solid species containing Cr3+. The surface film contained a mixture of oxidised zinc and chromium, probably in the form of basic zinc carbonate (hydrozincite) and hydrated chromia. Importantly strontium ions were found to play no significant role in the inhibition process.