Immersion Corrosion of Sn-Ag and Sn-Bi Alloys as Successors to Sn-Pb Alloy with Electronic and Jewelry Applications

A comparative investigation on the degradation in two distinctive corrosive media (NaCl and ethanol) of Sn-2 wt% Ag, Sn-10 wt% Bi, and Sn-22 wt% Pb alloys and the traditional Sn-40 wt% Pb alloys is performed. The deterioration is represented by both weight variation and corrosion rate in both 0.9% NaCl solution and anhydrous ethanol. It is shown that both uncoated and gold-plated samples are more susceptible to deterioration in NaCl than ethanol medium. A mechanical-to-corrosion (M/C) ratio is determined for each examined alloy. Considering the relative weights and costs associated with both M/C ratio and environmentally-friendly aspects, the Sn-Bi alloy is a potential successor for the traditional Sn-Pb alloys.