Abstract

The inhibiting action of thiourea and imidazole towards corrosion for carbon steel in open recirculating cooling system (ORCS) of Numaligarh Refinery Limited (NRL) , Golaghat , Assam,India has been studied in presence of Zn2+(as ZnSO4.7H2O) by weight loss and potentiodynamic polarization methods. The values of inhibition efficiency from weight loss method are in good agreement with those obtained from polarization studies. Polarization study indicates that imidazole retards the cathodic corrosion reaction where as thiourea inhibits anodic corrosion reaction in these particular blends of inhibitors. SEM and EDS study confirm the formation of an adsorbed protective film on the carbon steel surface.

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