The electroformation of normalAgCl during electro‐oxidation of Ag in neutral normalNaCl solutions is investigated by using potentiostatic and potentiodynamic techniques complemented with SEM observation and EDAX. The kinetics of the electroformation of normalAgCl is interpreted through a complex model that implies the formation of adsorbed normalAgCl species at the submonolayer level, the electrodissolution of Ag through the normalAgCl submonolayer diffusing out of the electrode as a complex ion, and the nucleation and growth of a tridimensional normalAgCl phase. This layer is formed initially as an island‐type deposit that includes normalAgCl precipitation from the solution adjacent to the electrode. The overall process is discussed in terms of a sum of nucleation and growth reactions under diffusion control (multiple region process). The electrode surface is considered as a sum of regions, each one involving its own characteristic growth rate. A probabilistic distribution of regions is postulated to calculate the current transients under a constant potential step. Fitting parameters can be reasonably interpreted at the molecular level. The proposed mechanism correlates with the complex chemical and electrochemical reactions expected for Ag in normalNaCl solutions.

The localized corrosion of mild steel in alkaline solutions containing a salt with a sulphurcontaining anion (sodium sulphate, sodium sulphite, sodium thiosulphate, potassium thiocyanate and sodium sulphide) is studied by using potentiostatic and potentiodynamic techniques complemented with scanning electron microscopy. Alkaline solutions containing one of those salts produce pitting of mild steel at potential values more positive than those of the active-passive transition of iron in base. In the presence of either thiocyanate or thiosulphate anion iron pitting takes place through sulphide formation which reacts at the electrode surface yielding poorly protective ferrous sulphide. At potential more positive than the breakdown potential the kinetic behaviour fits a competitive surface reaction mechanism involving the formation of the passive film and the nucleation and growth of a ferrous sulphide salt layer. The proposed reaction model reproduces the corresponding experimental current-transients.

Potentibstatic transients related to the electrolytic oxidation of molten thiocyanate (KSCN and KSCN + NaSCN, 0.7 : 0.3 mol/mol) on polycrystaliine ft obtained in the 168-290°C range are interpreted in terms of a nucleation and growth mechanism under diffusion control whieb involves the formation of two different products ~s~tuting the passivating anodie layer_ The different adjustable parameters are compatibte with the possible mokcular stxucture of the anodic layer.

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