شهرام قاسمی میر

Stainless steels have corrosion resistance in a wide range of environments by creating an oxide (passive) film. However, in aggressive environments such as seawater including the chloride (Cl-) ions, film decomposition occurs and leading to pitting corrosion [1]. Therefore, it may become vital to protect them against detrimental effects. Application of inhibitor is an important method to protect metallic materials versus corrosion deterioration. Despite inhibition efficiency of many organic and inorganic compounds, most of them are highly toxic. So, there exists the need to replace them by “green inhibitors” such as amino acids which have been reported as environmental friendly corrosion inhibitors because they are innoxious, biodegradable, soluble in aqueous media [2]. In this work, the inhibitive effect of thin coating based on a layer assembly of two amino acids (cysteine and glycine) on the 304 ss in simulated seawater was studied by tafel polarization technique. It is observed that the Ecorr values were shifted slightly to the positive region. The corrosion potential for the bare, Glycine (0.1M) and cysteine (0.005M) coated 304ss in 3.5% NaCl solution are -0.27V,-0.2V and -0.13V, respectively. Furthermore the Tafel analysis of Glycine (0.1M) and Cysteine (0.005M) coated 304ss reveal inhibitory efficiency (75.3%) and (96.8%) respectively. These results indicates the mode of inhibition is mainly anodic type of inhibition.