Electrochemical study on corrosion behaviour of zircaloy-2 in aqueous medium containing permanganate ion

The corrosion compatibility of zircaloy-2 was studied in strong oxidising permanganate based acidic (HMnO4) medium using impedance spectroscopy and potentiodynamic anodic polarisation methods at room temperature (28°C) and elevated temperatures (65 and 90°C). The average corrosion rate of zircaloy-2 in HMnO4 medium (0·417–8·33 mM) was found to be 1·32×10−4 μm h−1 at 28°C, 2·59×10−4 μm h−1 at 65°C and 3·53×10−4 μm h−1 at 90°C. At 28°C, the polarisation resistance Rp values obtained from impedance spectrum were higher (in kΩ) when compared to Rp values at 65 and 90°C, indicating a lower corrosion rate at lower temperature. Comparative studies with 2·5 mM H2SO4 and platinum (as a working electrode) showed the effects of oxidising nature and participation of additional redox reactions in HMnO4 medium. Cyclic polarisation studies showed the absence of pitting attack on zircaloy-2.