Corrosion performance of metals under protective coatings are governed by the physical nature of the coatings and the exposure environments. In this study, the behavior of coated AA 6111-T4 towards filiform corrosion or blistering was investigated via standard accelerated corrosion tests (ASTM G-85 Annex 2 (A2), ASTM B368, and EN 3665).(1)(2) The study involved several coating systems consisting of various pretreatments and an electrodeposited organic coating. The corrosion protection performance was characterized in terms of corrosion morphology, corrosion spread, and coating barrier property as a function of exposure times in the three test environments. The corrosion initiation and underpaint corrosion morphology are influenced by the mode of testing. Additional effect from the coating system and presence of oxidants govern corrosion propagation.

Subject
Accelerated corrosion tests, Test methods, Electrochemical impedance spectroscopy, Barriers, Coating performance, Coatings, Corrosion initiation, Phosphates, Pretreatment, Corrosion propagation, Corrosion protection, Barrier coatings, Coating systems
Keywords:
aluminum, AA6111, coating, pretreatment, corrosion, Electrochemical Impedance Spectroscopy, ASTM G85, ASTM B368, EN 3665
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2019
Association for Materials Protection and Performance (AMPP)
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