Electrochemical methods of corrosion assessment

Electrochemical impedance spectroscope, potentiodynamic polarization, and linear polarization based electrochemical methods are widely used in corrosion monitoring and to describe the corrosion inhibition mechanism of organic corrosion inhibitors. Obviously, electrochemical methods are used to support weight loss study. Numerous parameters can be derived using electrochemical methods in the term of which various aspects of corrosion and its mitigation are generally described. Generally, the compounds that increase the values of charge transfer resistance (Rct) are called as interface-type corrosion inhibitors. These compounds adsorb at the interface of metal surface and environment (electrolyte). Similarly, the potentiodynamic polarization method provides numerous parameters including corrosion potential (Ecorr) and corrosion current densities (icorr). Most of the compounds become effective by retarding both anodic and cathodic Tafel reactions without any appreciable change in the magnitude of Ecorr. Corrosion inhibitors can be divided as anodic- or cathodic-type if the displacement in the Ecorr values of inhibited and uninhibited Tafel curves is more than –85 mV, otherwise mixed type. The present chapter talks about the advantages and disadvantages of electrochemical methods of corrosion monitoring.