The effect of permanent magnet stirring on the corrosion resistance of Sn-2.0Ag-0.5Cu-2Zn solder alloys in NaCl solution

Abstract

Permanent magnet stirring (PMS) is adjusted to increase the alloy corrosion resistance by modifying the crystallographic texture. According to the findings, the lamellar structure had been converted into equiaxed grains by the PMS processing. Following exposure to a 3.5 wt percent NaCl solution, the corrosion behavior of the Sn-2.0Ag-0.5Cu-2Zn alloy was examined using electrochemical methods (polarization and electrochemical impedance spectroscopy (EIS)) and surface analysis using SEM, EDX and XRD. According to the PDP curves, the PMS treatment procedure significantly reduces the values of corrosion current density (icorr) and shifts the corrosion potential (Ecorr) to more positive noble values. The Ecorr values of SAC (205)-2Zn and SAC (205)-2Zn with PMS are increased from −936.66 to −756.18 mV (vs. SCE). Also, the pitting resistance is higher in case of PMS treated alloy as indicated from cyclic polarization (CP). PMS treated alloy possess higher Erep values than Ecorr values, confirming the ability of passive film to restore itself. EIS data showed that the diameter of capacitive loop for PMS-treated SAC (205)-2Zn alloy is approximately four times as the untreated alloy indicating less corrosion rate and higher protection.