The role of cathode distribution in gas/liquid/solid multiphase corrosion systems

Cathode distribution on a metal surface, depending on the total length of three-phase boundary per unit area (L _tpb), is an important factor influencing corrosion behavior of metals in gas/liquid/solid multiphase corrosion systems. The effect of L _tpb on cathodic oxygen reduction process was first studied by steady-state polarization technique, and the result showed that the cathodic-limiting current densities linearly increased with increasing L _tpb, indicating that the cathode distribution had an important influence on the corrosion behavior of metals. On this basis, a model is developed to establish the correlation between the cathodic-limiting current and L _tpb. In the model, a general expression for the cathodic-limiting current distribution in TPB zone is deduced, and a linear dependence of the total cathodic-limiting current density on L _tpb is established. The simulation result is in good agreement with experimental data.