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

Abstract

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 R _p values obtained from impedance spectrum were higher (in kΩ) when compared to R _p 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.