engleski

Kinetics of anodic oxide film growth on tin : ionic transport across a barrier in the high field limit

Nucleation, formation and growth of thin oxide films on tin in a slightly alkaline borate buffer solution were studied using cyclic voltammetry and galvanostatic techniques. The results indicated the dissolution-precipitation mechanism for primary passivation of tin in dynamic conditions. The oxide film formation process is under ohmic resistance control. The change in ohmic resistance is caused by the nucleation and spread of the reaction products as a layer on the metal surface. The reduction of anodic oxide film is limited by resistance in the pores between the deposited metal sites. In the galvanostatic conditions film growth occurs by activation-controlled ionic conduction by high electric field across the film, according to the exponential law. The following kinetic parameters of film growth were estimated: 1. (i) constants A and B of the exponential law, 2. (ii) the electric field which is of the order 106 V cm−1, 3. (iii) effective activation distance, a* for the ionic jump over the energy barrier associated with cation transport within the oxide layer.

tin; anodic oxide film growth; ionic transport; high field limit

nije evidentirano