Anodic oxide films on tin in carbonate-bicarbonate buffer solution

Steady-state polarisation curves, voltammetric electroreductions and impedance data were used to analyse passive films anodically formed on tin in carbonate-bicarbonate buffer solution of pH 8.9. Over the potential range −0.1 V/1.2 V (SCE), tin exhibits an essentially potential independent steady-state passive current, which is also independent of hydrodynamic conditions. Some evidence was presented indicating that the anodic oxide film on tin is an oxygen ion conductor. The diffusion coefficient of defects in the film was estimated. Likewise, for different formation potentials oxide thickness was calculated by two independent experimental methods. The thickness of the barrier layer varies linearly with the applied voltage.