Effect of Layer Thickness and Temperature Difference on Oxygen Diffusion Behavior in Thin Solution Layer Formed on Metal

Abstract

One of the controlling factors for atmospheric corrosion is oxygen diffusion behavior in thin solution layer formed on metals. The oxygen diffusion limiting current in thin solution layer formed on Zn electrode was measured electrochemically to clarify the influence of solution layer thickness, temperature difference in the solution layer on the oxygen diffusion behavior. A solution of 10 mM NaCl was used as electrolyte to form solution layers. The solution layer thickness was controlled by masking adhesive tape with through holes. The environmental temperature, T_E, was controlled by circulating temperature-controlled water and the sample temperature, T_S, was controlled by a Peltier device. At T_E = T_S, the oxygen limiting current was independent of solution layer thickness. At T_E < T_S and the solution layer thickness thinner than 0.6 mm, the oxygen diffusion limiting current increased with thinning of the solution layer. The results suggest that T_E and T_S are also take into account as estimation of steel corrosion rate at snowy and cold region.