Influence of applied potential on tin content in electrodeposition of Zn-Sn alloy coatings and its effect on corrosion protection

In the present work, the electrochemical deposition of Zn-Sn alloy at different applied potentials is studied. The deposits were prepared from a chloride bath on a stainless steel substrate (SS) using cyclic voltammetry, chronoamperometry and anodic linear stripping voltammetry methods. X-ray diffraction, scanning electron microscopy and energy dispersive were used to study the structural, morphological and chemical composition of the deposits. The corrosion behavior of the elaborated samples was studied by open circuit potential (OCP), Tafel plot and electrochemical impedance spectroscopy (EIS) in 3.5 wt-% NaCl solution. Results indicated that the Zn-Sn alloy coatings exhibit a synergistic property combining the barrier behavior afforded by Sn and strong passive behavior of Zn. Electrochemical measurements obtained by Tafel and EIS plots revealed that Zn-Sn alloy coatings obtained at more positive potential of -1.1 V present best corrosion resistance.