Anodic film formation on silver in solutions containing chromate

VERONICA BRUNETTI; H. M. VILLULLAS; M.LÓPEZ TEIJELO

ELECTROCHIMICA ACTA

Elsevier

Año: 1999 p. 2843 - 2851

0013-4686

The anodic behaviour of silver electrodes in aqueous sodium chromate solutions has been studied by linear potential sweep voltammetry and potentiostatic current transients. The formation and growth of the passivating Ag2CrO4 film is a complex phenomenon that involves a sequence of several processes. The rate of salt film formation is initially controlled by a three-dimensional progressive nucleation process with difusion-controlled growth. When surface coverage increases the contribution of the resistance of the layer-pore system is apparent. The induction time obtained in the current transients can be associated with the build-up of a critical concentration of silver ions near the electrode surface to produce the precipitation of the solid material on the electrode.