Previous research has shown that electrochemical techniques can be used to provide quantitative measures of corrosion performance for conversion coatings on aluminum alloy 2024-T3.1 These techniques could replace the lengthy, costly neutral salt spray test with a few hours of electrochemical testing. This testing provides numerical and statistical comparisons of coatings, which is more robust than the subjective and qualitative analysis performed visually during salt spray testing. Consistent relationships are seen on two common aerospace aluminum alloys (2024 and 7075) coated with two different conversion coatings. Results show predictive correlations between salt spray testing and electrochemical testing. Improvements in corrosion resistance during salt spray had more negative open circuit potentials, lower polarization resistances, larger polarization resistance slopes, and lower corrosion rates measured via electrochemistry. We conclude that electrochemical testing could be an affordable, efficient, quantitative replacement for neutral salt spray testing.

Key words: chemical treatment, coating (process), coatings, corrosion control, electrochemistry, corrosion monitoring, surface finishing, test methods, thin films