Study of corrosion behavior of Pb–Ag alloy electrodes in the zinc sulfuric acid solution by scanning reference electrode technique

Abstract

The corrosion behavior of four commercial Pb–Ag alloys electrodes in the zinc sulfuric acid solution was investigated using scanning reference electrode technique (SRET). The results show that SRET is more sensitive for studying not only the uniform corrosion behavior of the Pb–Ag electrodes, but also the localize corrosion of the Pb–Ag electrodes. Under free corrosion conditions, lead corrosion (anodic) zone appeared on the edge of electrode while hydrogen evolution reaction (cathodic) zone appeared on the centre of the specimen. The absolute anodic potential and localize corrosion of the four electrodes decreased with the increase of immersion time. At the end of 10 h of free corrosion condition, the electrode Pb-0.69% Ag alloy displays the best corrosion resistance, followed by the electrodes Pb-0.62% Ag alloy, Pb-0.25% Ag-0.1% Ca alloy and Pb-0.56% Ag alloy. During polarization study and potential decay, the electrode Pb-0.69% Ag alloy had the lowest Quasi Electromotive Force (QEMF), followed by the electrodes Pb-0.62% Ag alloy, Pb-0.25% Ag-0.1% Ca alloy and Pb-0.56% Ag alloy, it means that the electrode Pb-0.69% Ag alloy had the highest corrosion resistance, followed by the electrodes Pb-0.62% Ag alloy, Pb-0.25% Ag-0.1% Ca alloy and Pb-0.56% Ag alloy in the zinc sulfuric acid solution. Also, linear polarization confirms the same trend as that of the SRET.