Effect of length of gas/liquid/solid three-phase boundary zone on cathodic and corrosion behavior of metals

Liquid dispersion, depending on the length of gas/liquid/solid three-phase boundary (TPB) zone of dispersed liquid on a metal surface, is an important property of liquid state influencing corrosion behavior of metals in gas/liquid/solid multiphase corrosion systems. The effect of TPB length on the cathode and corrosion process was studied using steady state polarization technique, electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) technique. It was found that both the cathodic limiting current density and corrosion current density linearly increased with increasing the TPB length, indicating that the cathodic and corrosion process in gas/liquid/solid multiphase corrosion systems not only depended on the thickness of liquid layer but also strongly depended on the dispersed liquid state on a metal surface. In addition, a model is developed to establish the relationship between the cathodic limiting current density and the TPB length. The simulation result is in good agreement with the experimental findings. The model is also useful for evaluating the effect of liquid dispersion on atmospheric corrosion rates. (C) 2008 Elsevier Ltd. All rights reserved.