EVALUATION OF ELECTROCHEMICAL CORROSION FOR MILD STEEL EXPOSED TO DIFFERENT CHLORIDE MEDIA.

Abstract

The influence of different chloride media such as 3.5%NaCl, 10% NaCl, Vätäänen nine salt solutions (VNSS) prepared as artificial seawater and natural seawater on the corrosion of mild steel (MS) has been studied using electrochemical polarization techniques. The effect of the addition of starch, glucose, yeast extract, peptone, and mixture of growth media on the corrosion behavior of mild steel has been also discussed. The order of the rate of decrease in oxide film thinning proceeds according to the following order of the type of the applied medium: 10%NaCl > seawater > VNSS > 3.5%NaCl. On the other hand in case of mild steel immersed in VNSS in presence of different nutrients the rate of oxide film thinning proceed according to the following order of the type of growth medium: Peptone < glucose < yeast extract < mixture of growth media ≈ starch. Seawater was found to be less corrosive than VNSS. Addition of the growth media induced a decrease in both the cathodic and anodic currents and acted as a mixed type inhibitor. Cyclic polarization scans illustrate little decrease in the pitting tendency in the presence of growth media.