Application of Electrochemical Techniques: Corrosion Inhibitors on Steel.

Electromechanical techniques were used to study the corrosion of metals in aqueous environments to determine whether the anodic or cathodic process, or both, controls corrosion and the mechanism of film-formation or dissolution. Potentiostatic and potentiodynamic polarizations were conducted on mild steel in neutral and salt solutions, and on mild steel coated with various sulfonate inhibitors in salt solutions. Corrosion rates of mild steel and of mild steel coated with sulfonate inhibitor were determined by use of the Tafel extrapolation and the linear polarization methods. Salt solutions caused a reduction in the span of the passive range and caused dissolution of the mild steel at a lower potential when compared with mild steel in neutral solutions. The adsorption of sulfonate inhibitors on mild steel caused a lower initial rest potential and a lower current density. The Tafel extrapolation and the linear polarization methods gave reproducible corrosion rates for mild steel alone. However, only the latter method could be used to determine the corrosion rates of mild steel coated with an inhibitor. Author