Electrochemical behavior of Zn-xSn high-temperature solder alloys in 0.5 M NaCl solution

Publication date: 5 September 2017
Source:Journal of Alloys and Compounds, Volume 716
Author(s): Zhenghong Wang, Chuantong Chen, Jinting Jiu, Shijo Nagao, Masaya Nogi, Hirotaka Koga, Hao Zhang, Gong Zhang, Katsuaki Suganuma
Electrochemical behavior of Zn-xSn (x = 40 wt%,30 wt%,20 wt%) high-temperature lead-free alloys was investigated in aerated 0.5 M NaCl solution by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. OCP results show that the corrosion state of the alloys working surface reached a relatively dynamic equilibrium after the alloys were immersed in 0.5 M NaCl solution for 100 h. EIS analysis reveals that the total corrosion resistance Rt of alloys depended on the amount of Sn, and Zn-40Sn possessed the highest value 2228.2 Ω cm². No passivation behavior was observed during corrosion process by potentiodynamic polarization measurement. The dominant corrosion products were confirmed as Zn5(OH)8Cl2·H2O, ZnO and Zn(OH)2. Moreover, the surface and cross-section morphology of corrosion product suggested that the corrosion layer was more homogeneous and denser for higher Sn-content, Zn-40Sn obtained the best protective layer from corrosion product. The results recommend that Zn-xSn high-temperature solder alloy with higher Sn content appears to be more attractive in terms of superior corrosion properties. The exact corrosion process was also discussed in detail.



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