The corrosion behavior of Al-Zn alloys in Abakaliki and Port Harcourt rainwater

A study has been carried out on the corrosion behavior of Al - Zn alloys exposed to rainwater sourced from Abakaliki, Ebonyi State, a highly residential urban town and Port Harcourt Rivers State, a highly industrialized urban town, both in Nigeria. Corrosion test coupons of four (4) differing alloy grades of varying Zn concentrations produced at First Aluminium Plc., Port Harcourt under carefully controlled atmosphere were immersed in beakers containing each of the rainwater separately. The setup was allowed to stand for 30 days with a set withdrawn 5-daily for corrosion rate evaluation using the normal procedures. Results showed that all the alloy grades followed the usual corrosion trends associated with passivating metals, but that samples exposed to Abakaliki rainwater were more severely attacked, possibly due to the heavy presence of clouds of carbonate particles in the atmosphere generated from predominant quarrying works in the town which must have made the rainwater somewhat acidic as compared to the possible presence of flared glasses in Port Harcourt resulting from petrochemical refining operations that predominate the town.