Corrosion behaviour of Sn-9Zn-xS solders in 3.5 wt-% NaCl solution

Abstract

The effects of S addition on the corrosion behaviour of Sn-9Zn solders in 3.5 wt-% NaCl solution were investigated using dynamic potential polarisation, electrochemical impedance spectroscopy techniques and weight loss measurement. The results indicate that S addition could obviously improve the corrosion resistance of Sn-9Zn solder alloy as revealed by much lower corrosion current density, higher impedance and the reduced weight loss. It is believed that the homogeneous microstructures of Sn-9Zn, especially the black refined Zn-rich phases are favourable to improve its corrosion resistance. SEM observations found that S addition might promote the formation of denser and more uniform corrosion products on the solder surface. The main corrosion product was Zn₅(OH)₈Cl₂·H₂O determined by EDS and XRD analysis.

KEYWORDS:

• Lead-free solder
• Sn-Zn
• sulphur
• corrosion
• electrochemical impedance spectroscopy

Acknowledgements

The work was supported by the Natural Science Foundation of Jiangxi Province under grant No. 20181BAB206010.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Natural Science Foundation of Jiangxi Province [grant number 20181BAB206010].