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. - Highlights: • The electrochemical behavior of Pb–Ca–Sn–Sm alloy in H₂SO₄ solution is studied. • Corrosion evaluation, pitting tendency and ac/dc electrochemical measurements. • Sm inhibits the growth of the anodic film and improves the corrosion resistance. • Sm can severely promote the pitting corrosion tendency of Pb–Ca–Sn alloy.