Kinetics of Aqueous Corrosion

This chapter presents the forms of energy dissipation involved in a corrosion process when a positive driving voltage is available for corrosion to take place, as defined by thermodynamics, and how they concur to determine the overall corrosion rate. Dissipations are described in terms of overvoltage of the different processes involved, which are classified as activation overvoltage (metal corrosion, hydrogen evolution), represented by Tafel law, concentration overvoltage (oxygen diffusion) and ohmic drop (electrolyte resistivity). The trend of the overvoltage for an active-passive metal is also described in the different potential ranges, corresponding to immunity, activity, passivity and transpassivity (or localised corrosion).