Computational Simulation of Galvanic Corrosion under the Thin Film of Electrolyte

corrodes. The metal with the higher OCP acts as a cathode. On the cathode, reduction takes place. In the case of galvanic corrosion it is termed as depolarization. Electrolyte enables transport of the ions and the conductive connection closes an electric circuit. Electric current flowing between the electrode and the electrolyte causes a shift in the electrode potential. This phenomenon is called polarization. Polarization is a complex phenomenon influenced by kinetics of the processes on the electrode/electrolyte interface [Jones 1996, Schweitzer 2010]. The dependence of electrical potential of an electrode on a current density is called polarization curve. Two conductively connected metals settle their potentials at the same value, called corrosion potential, given besides their OCPs by areas of their surfaces. The areas influence the current density. Between the electrodes flows the corrosion current. OCPs describe the thermodynamics and the polarization curves describe the kinetics of galvanic corrosion. The evaluation of corrosion is possible in many different ways. Visual evaluation is possible e.g. according to international standard ČSN EN ISO 10289. Quantitative criterion for the evaluation is the mass loss rate and the corrosion rate. In the case of galvanic corrosion this values are connected with the density of corrosion current through the Faraday’s law: