Electrochemical Behavior of Vanadium in Azide Electrolyte in Comparison with the Behavior in Halogen Ions-Containing Electrolytes

The influence of azide ion concentration and temperature on the electrochemical behavior of vanadium was studied using open-circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The steady state potential (Ess) is a linear function of azide ion concentration. Polarization measurements have shown that the rate of corrosion icorr increases with increasing the azide ion concentration as well as increasing solution temperature. EIS investigations under open-circuit conditions confirm these results as can be identified by the decrease of the polarization resistance (Rox) and oxide thickness (1/Cox) with increasing the azide ion concentration. The measured impedance responses were analyzed using a constant phase element (CPE) model with its complex transfer function. The behavior of vanadium in the azide medium is also compared to that in other halide salt solutions, it was found that the tendency for spontaneously grown thicker oxide film increases in the order: Br￣ > Cl￣ > I￣ > N 3 ￣ > F￣.