Corrosion and fretting-corrosion behavior of Zr-Nb alloy under aqueous LiOH solution

Abstract

Zirconium alloys are the key materials for nuclear reactor’s core components due to low neutron cross-section and good mechanical and corrosion properties. During operation in nuclear reactor, some core components (exposed to the corrosive environment of coolant water having LiOH) may undergo corrosion and fretting-corrosion. This work presents a novel experimental approach for investigating the Zr-2.5 Nb alloy's corrosion and in-situ fretting-corrosion response. The corrosion analysis was performed using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization, to study the effect of LiOH concentration in water and exposure duration. It is observed that the corrosion rate increases with increasing the concentration of LiOH in water and decreases with increasing the exposure duration. The fretting-corrosion tests were performed between SS-410 and Zr-2.5 Nb in aqueous LiOH solution. The results reveal that the contact resistance and coefficient of friction (COF) decrease with increasing concentration of LiOH in the solution. The present work highlights the scientific understanding of corrosion and fretting-corrosion phenomena in zirconium alloy and elucidates key mechanisms and factors governing the degradation behavior which can help in preventing the failure of the components.