Abstract
The pace of coatings development is limited by the time required to assess their corrosion protection properties. This study takes a step forward from past studies and correlates the corrosion performance of protective coatings assessed by a series of short-term electrochemical measurements with 18 month and 60 month beachside atmospheric exposure results of coated panels. A series of 11 coating systems on A36 steel (UNS K02600) substrates were tested in a blind study using the damage tolerance test (DTT). In the DTT, a through-film pinhole defect is created, and the electrochemical characteristics of the defect are then monitored over the next 1 to 7 days while immersed in 0.5 M sodium chloride (NaCl). The results from open-circuit potential, anodic potentiostatic polarization, and electrochemical impedance spectroscopy tests were used to characterize the corrosion behavior of the coating systems. The beachside exposure tests were conducted at the Kennedy Space Center (Kennedy Space Center, Florida) according to ASTM D610-01. It was found that the short-term changes in the open-circuit potential and in the charge delivered during a sequence of potentiostatic pulses showed high correlation and even higher correlation to 60 month beachside atmospheric exposure with correlations approaching 100%.
