| Abstract Scope |
This study aims to investigate the electrochemical corrosion behavior of the potential Pb-free solders, Bi-11wt%Ag and Zn-40wt%Sn, in 3.5% NaCl solution using the potentiodynamic polarization method with the scanning range from -2000mV to +2000mV. Pb-5wt%Sn alloy is also examined for comparison. Experimental results show that the corrosion potential (Ecorr) decreases in turns from Bi-11Ag, Pb-5Sn, Zn-40Sn to Zn-40Sn-0.5Al. Bi-11Ag exhibits the highest current density (Icorr), and that for Pb-5Sn is the lowest. The Pb-5Sn samples have a much extended passive region compared to Bi-11Ag, while the Zn-40Sn samples show no passive behavior. According to the XPS data, the corrosion products are PbCl2 and PbO for Pb-5Sn, BiOCl, AgCl2, and Bi2O3 for Bi-11Ag, and ZnCl2, ZnO, SnO, SnO2 for Zn-40Sn. Furthermore, it is found that a small amount of Al addition improved the corrosion resistance of Zn-40Sn. |