The Role Of Liquid Dispersion In Gas/Liquid/Solid Multiphase Corrosion Systems

Liquid state on a metal surface is an important factor influencing corrosion behavior of metals in gas/liquid/solid multiphase corrosion systems. Liquid dispersion, one of important properties of liquid state, is closely related with the geometric properties of gas/liquid/solid three-phase boundary (TPB) zone of dispersive liquid on the metal surface. Therefore, studies of effects of geometric properties of TPB zone on cathodic and corrosion behavior of metals can reflect the important role of liquid dispersion in gas/liquid/solid multiphase corrosion systems.In this paper, steady-state polarization technique, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) technique, contact angle measurement technique, combined with microscopic observation technique, are employed to investigate the influence of TPB length, width and electrolyte concentration on cathodic and corrosion behavior of metals. The results show that both the cathodic limiting current density and corrosion current density linearly increase with increasing the TPB length and width, indicating that the liquid dispersion plays an important role in gas/liquid/solid multiphase corrosion systems.Further, a Kelvin probe technique is used to study the effect of electrolyte layer thickness on the cathodic limiting current density of TPB zone. On this basis, a model is developed to simulate the cathodic oxygen reduction process in this zone. Based on this model, effects of TPB geometric parameters on the cathodic limiting current density of metals are simulated, and the calculated results are in good agreement with the experimental data.Atmospheric and soil corrosion systems are typical of gas/liquid/solid multiphase and dispersive corrosion systems, in which liquid dispersion plays a vital role in the corrosion processes of metals. In atmospheric corrosion, the correlation between the liquid dispersion and TPB parameters is established, and the influence of liquid dispersion on the cathodic oxygen reduction process of atmospheric corrosion is simulated. The simulation results show that the cathodic limiting current of metals is linearly dependent on the liquid dispersion, confirming the important role of liquid state in atmospheric corrosion systems. In sandy soil corrosion, the variations of both TPB parameters and liquid dispersion with soil water content are investigated, and on this basis, the influence of liquid dispersion on the cathodic oxygen reduction process of sandy soil corrosion is simulated. The simulation results show that the cathodic limiting current density of metals linearly depends on the liquid dispersion, further confirming the important role of liquid state in sandy soil corrosion systems.