Electrochemical corrosion behavior of Pb-Ca-Sn-Sm grid alloy in H2SO4 solution

The electrochemical corrosion behavior of Pb-0.23 wt.% Ca-0.93 wt.% Sn and Pb-0.23 wt.% Ca-0.92 wt.% Sn-0.18 wt.% Sm alloys in 4.8 M H2SO4 at 25 °C was studied using open circuit potential (OCP), cyclic polarization, electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and Mott-Schottky plot. The findings of this study show that the samarium added to Pb-Ca-Sn alloy increases the general corrosion resistance of this alloy and inhibits the growth of the anodic corrosion layer, it can promote the pitting corrosion tendency of Pb-Ca-Sn alloy. Mott-Schottky plot also reveals that the anodic films on Pb-Ca-Sn and Pb-Ca-Sn-Sm alloys at +1.5 V vs. SCE exhibit an n-type semi-conductive character. Sm increases the slope of Mott-Schottky plot, implying the reduction of the defect density within the anodic film, which is beneficial to increase the resistance of anodic film.