Electrochemical behaviour of a Pb–Sb alloy in 0.5 M NaCl and 0.5 M H2SO4 solutions

A comparative experimental study on the electrochemical behaviour of a Pb–1 wt.%Sb alloy is carried out in a 0.5 M NaCl and a 0.5 M H2SO4 solutions at room temperature. A water-cooled unidirectional solidification system was used to obtain the Pb–Sb alloy samples used in the corrosion tests. Electrochemical impedance spectroscopy (EIS) plots, potentiodynamic polarization curves and an equivalent circuit analysis were used to evaluate the electrochemical behaviour. The experimental current density decreased with the increase in the cellular spacing, independently of the nature of the applied electrolyte. Hence, a dilute Pb–Sb alloy having coarse cell spacings has higher electrochemical corrosion resistance.

► Independently of nature of electrolyte, the microstructure determines the corrosion. ► Coarse arrays tend to yield higher corrosion resistance than fine arrays. ► In H2SO4 and NaCl solutions evidenced coarse array with better corrosion resistance.