Test panels of aluminum alloy 2024-T3 were painted with isocyanate and isocyanate-free topcoats and analyzed using electrochemical impedance spectroscopy (EIS). A total of 6 isocyanate-free and 1 isocyanate-containing topcoats were analyzed, both in the non-scribed and scribed conditions. All test panels were exposed to salt fog for 2000 hours and removed at specific time intervals for EIS measurements. The EIS characterizations were made in 0.1M sodium borate. Results suggest that there may be a relationship between the barrier properties of a topcoat and its resistance to scribe-induced corrosion where topcoats with relatively lower barrier resistance allow dissolution and transport of inhibitors to the defect site.

Subject
Primers, Electrochemical impedance spectroscopy, Barriers, Top coats, Impedance, Sodium chloride solution, Corrosion inhibitors, Salt spray corrosion testing, Immersion, Coating defects, Corrosion protection, Electrolytes, Coating systems
Keywords:
non-isocyanate, coatings, EIS
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2007
Association for Materials Protection and Performance (AMPP)
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