Reactivity of the oxide growth process on zr metal in aqueous potassium iodide and other alkali halide solutions

Abstract

The kinetics of growth of an oxide film on Zr electrode under open circuit conditions in K1 solutions were investigated using potential and impedance measurements. The effect of some parameters such as surface pre-treatment, concentration and salt type, including alkali halide anions, on the reactivity of the oxide growth process were studied. In all cases the potential, capacitance and resistance were followed with time, and the oxide film was found to thicken continuously.The iodide ion is assumed to participate in enhancing the formation of species which inhibits partially the growth of oxide film on Zr surface. The impedance diagrams of the oxide film/electrolyte interface is an almost capacitative one, with an impeded charge transfer reaction.

Corrosion behaviour of zirconium electrode in sodium azide electrolyte as compared to the alkali halide solutions

“…Higher rates of formation are usually associated with higher degree of surface and bulk imperfections in the oxide, such an oxide will be more reactive than the one grown at lesser rate (in the concentrated NaN 3 solution) characterized by better insulating properties. Similar behaviour has been reported previously for zirconium metal in KI solutions [29]. …”

“…This angle varies between a maximum limit of 908 for ideal dielectric surface oxide with excellent insulating properties and a minimum limit of 08 for the very reactive system. As shown in Table 2, the value of h reaches up to values close to 708 for the dilute 0.1 M solution and increases to about 808 for the concentrated 2.0 M solution, but since h < 908 it means that the metal/solution interface can not be considered as a perfect capacitor [29].…”