No abstract

No abstract

No abstract

The corrosion and passivation of polycrystalline iron electrodes in carbonate-bicarbonate solutions are studied in the 0-75°C temperature range. The influence of the solution ionic strength, stirring velocity, and potential scan rate on the electrodissolution of the base metal and the formation of both the prepassivating and the passivity surface layers are considered. The chemical dissolution of the prepassive film and the electroformation of the different surface compounds are discussed in terms of a complex reaction pathway involving both simultaneous and consecutive stages including the corresponding ionic equilibria.

The influence of ionic composition on the electrodissolution and passivation of iron electrodes in potassium carbonate/bicarbonate buffers is studied over the concentration range of anions compatible with the regulating capacity of the buffer, at 25°C, by using voltammetric and rotating disc electrode techniques. Data are discussed on the basis that the interaction between Fe 2÷ and HCO~ ions plays an important role at the outer part of the passivating layer where the local pH resulting from the thickening of the passivating layer is determined by the coupling of different ionic equilibria.