Role of hygroscopic chloride salts on corrosion performance and hydrogen absorption of steel under cyclic wet-dry conditions

Abstract

The corrosion morphology of steel under aqueous NaCl, MgCl2, and ZnCl2 droplets and the corresponding hydrogen permeation behaviour were investigated using surface characterization techniques and electrochemical methods. Under cyclic wet-dry conditions, Mg2+ and Zn2+-containing surface layers were formed on steel and the latter presented a high corrosion resistance. The most active hydrogen entry occurred under ZnCl2 during drying, while it happened under MgCl2 at low humidity. The effects of chloride salts on the formation of rust layers and hydrogen entry into steel during wet-dry cycles were discussed based on the hardness of metal cations and the deliquescence properties of salts.