Mechanism of Zinc Corrosion in Accelerated Corrosion Tests

ABSTRACT Understanding into the effect of parameters of cyclic accelerated corrosion tests on the corrosion response is essential for proper test design and interpretation of results. Real‐time corrosion rate of zinc was measured using electrical resistance sensors and statistically evaluated in seven tests. The chloride deposition phase was the most corrosive, influencing the corrosion behavior throughout the tests. Despite corrosion deceleration between chloride deposition events, zinc was repeatedly reactivated by the application of NaCl solution and zinc corrosion rate increased during the tests. It is in contrast to field observations. Prolonged exposure to high humidity and elevated temperature during the transition and wet phases accelerated corrosion, while prolonged drying at higher temperature inhibited corrosion. The results suggest that the corrosivity of future corrosion tests needs to be reduced by lowering the salt concentration, shortening the chloride deposition phase, and including sufficiently intense drying.