Enhanced corrosion resistance properties of mild steel in neutral aqueous solution by new ternary inhibitor system

Abstract

The goal of studying corrosion process is to find means of minimizing corrosion or prevent it from occurring. The use of inhibitors is one of the most popular methods for corrosion protection. A protective film has been formed on the surface of mild steel in neutral aqueous environment using a synergistic mixture of an eco-friendly inhibitor viz., Vitamin B1 (Thiamine hydrochloride) along with Iminodi(methylphosphonic acid) (IDMPA) and Zn2+ ions. The inhibitive effect of Vitamin B1, IDMPA and Zn2+ ions has been investigated by gravimetric studies, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The investigations revealed that Thiamine acts as an excellent synergist in corrosion inhibition. Optimum concentrations of all the three components of the ternary formulation are established by gravimetric studies. Potentiodynamic polarization studies inferred that this mixture functions as a mixed inhibitor. EIS studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of mild steel. Surface characterization techniques (FTIR, SEM and AFM) are also used to ascertain the nature of the protective film. The mechanistic aspect of corrosion inhibition is proposed.