Electrochemical Behavior Assessment of Zircaloy-4 in Nitric Acid Solutions by Electrochemical Impedance Spectroscopy and Mott- Schottky Analyses

Zircaloy-4, one of zirconium alloys, has outstanding corrosion resistance to nitric acid. Utilizing potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott–Schottky analyses, the electrochemical behavior of zircaloy-4 in nitric acid solutions were evaluated under open circuit potential (OCP) condition. At first, where the concentration of nitric acid increased from 0.01 to 0.05 M, the corrosion current density decreased. However, it amplified rapidly while the concentration increased from 0.05 to 0.50 M. Moreover, the EIS studies demonstrated an inverse trend for polarization resistance values. Mott–Schottky analysis indicated that the passive films displayed p-type semiconductive characteristics. Also, this analysis showed that the acceptor densities decreases by increasing nitric acid concentration from 0.01 to 0.05 M, whereas it increases when the nitric acid concentration reaches from 0.05 to 0.50 M. This trend was consistent resulting in potentiodynamic polarization and EIS measurements.