Effects of Organic Corrosion Inhibitors on the Electrochemical Characteristics of Zinc in Alkaline Media

The electrochemical characteristics of zinc in 8 M potassium hydroxide (KOH) electrolyte containing polyethylene glycol (PEG) were investigated. It was found that PEG400, as well as PEG600, could dramatically decrease the corrosion current within an extremely short time. Additionally, the protection efficiency of the PEG600 was superior to the PEG400. During the first ten days of storage, the PEG600 provided a rather high protection efficiency, >90%, to zinc from corrosion. However, an abrupt drop of protection efficiency, about 16%, was observed afterward. This decline of protection efficiency of PEG was in agreement with the decreases of film resistances derived from alternating current (AC) impedance measurements. Three distinct equivalent circuits were proposed to explain the variations in impedance characteristics during the long-term storage time.