Characterization of the Corrosion Products Formed on Zinc in Archipelagic Subtropical Environments

摘要

The atmospheric corrosion of zinc samples exposed at 25 test sites with different climatic and pollutionconditions was investigated during a two-year exposure program carried out in three of the CanaryIslands (Spain) as to cover the typical range of subtropical environmental conditions. The compositionand distribution of the corrosion products of zinc were analyzed qualitatively by X-ray diffraction(XRD). Simonkolleite (Zn5(OH)8Cl2) and hydrozincite (Zn4CO3(OH)6H2O) were the corrosionproducts more frequently observed, revealing that chloride and carbon dioxide are the most aggressivepollutants present in the atmosphere. Sulphate-containing species, namely Zinc oxysulfate(Zn3O(SO4)2), Zinc hydroxysulfate (Zn4SO4(OH)6), Zinc diamminehydroxynitrate(Zn5(OH)8(NO3)22NH3) and zinc chlorohydroxysulfate (NaZn4Cl(OH)6SO46H2O), were also foundthough in smaller amounts.