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 (HMnO 4 ) medium using impedance spectroscopy and potentiodynamic anodic polarisation methods at room temperature (28uC) and elevated temperatures (65 and 90uC). The average corrosion rate of zircaloy-2 in HMnO 4 medium (0?417-8?33 mM) was found to be 1?326 10 24 mm h 21 at 28uC, 2?59610 24 mm h 21 at 65uC and 3?53610 24 mm h 21 at 90uC. At 28uC, the polarisation resistance R p values obtained from impedance spectrum were higher (in kV) when compared to R p values at 65 and 90uC, indicating a lower corrosion rate at lower temperature. Comparative studies with 2?5 mM H 2 SO 4 and platinum (as a working electrode) showed the effects of oxidising nature and participation of additional redox reactions in HMnO 4 medium. Cyclic polarisation studies showed the absence of pitting attack on zircaloy-2. Experimental Materials and solutionsThe sample coupons of zircaloy-2 (Zr-1?5Sn-0?15Fe-0?1Cr-0?05Ni; size, 161 cm) were polished with different grades of silicon carbide papers ranging from 80 to