Aspects on Early-Stage Corrosion of Different Zinc Alloys : Wet scCO(2)-Induced Corrosion

Abstract

The surface activity of different zinc alloys was evaluated in wet scCO(2). The zinc coating surface chemistry governed the corrosion product formation. On zinc and Zn-Al coatings, the Al2O3 layer prevented growth of corrosion products. A Zn-Al-Mg coating showed high initial reactivity due to active Zn-Mg phases. An electrogalvanized coating was very active due to a high ratio of exposed, less dense planes. In a Zn-Fe coating, several Zn-Fe phases were susceptible to wet scCO(2) at the same time, triggering the sacrificial effect of Zn. Wet scCO(2) is a convenient medium to assess the early-stage corrosion of metal coatings.