Hydrogen absorption behavior into Zn and Zn'Al coated steels during corrosion in aqueous solutions

Abstract

In this study, hydrogen absorption behavior into Zn and Zn-55mass%Al coated steels was investigated both in an immersion test and a wet and dry cyclic corrosion test with NaCl and Na2SO4 solutions by Devanathan-Stachurski permeation technique. In the immersion test, the hydrogen absorption into Zn coated steels was observed after the surface of the steel substrate under Zn coating was exposed to corrosion environments. On the other hand, hydrogen absorption into Zn'Al coated steels was not observed for the duration of the tests because of slower dissolution kinetics of Zn'Al coating than Zn coating in the corrosion environments. In the case of a wet and dry cyclic corrosion test, hydrogen permeation current for Zn coated steel was observed during the test duration only under the condition with NaCl solution. This may be because dissolution of Zn coating takes place more locally in NaCl solution than in Na2SO4 solution. These results were discussed based on corrosion rate of the coating of Zn and Zn'Al alloy and on corrosion morphology of Zn and Zn'Al alloy coatings in NaCl and Na2SO4 solutions.