Structure, composition and corrosion studies of Zn, Cu, Sn and their alloys electrodeposited from a deep eutectic solvent

In this thesis, platinum and steel were coated with metals (Cu, Zn and Sn), binary alloys (Cu-Zn, Cu-Sn and Zn-Sn) and a triple alloy (Cu-Zn-Sn) by electrochemical method. The corrosion behaviour of these films were investigated in 3.5% NaCl solution. Chlorine chloride-ethylene glycol based ionic liquid was used for electrodeposition of metals and alloys. The plating process was carried out on platinum and steel by a three electrode system by applying constant potential. As metals/alloys were electrodeposited potentiostatically, chronoamperometric graphs of deposition were obtained. The resulting coated samples were analyzed by SEM, XRD/EDAX and optical microscope. Potentiodynamic polarization (Tafel Plot) was applied to understand the corrosion mechanism of uncoated and coated samples in 3.5% NaCl. Corrosion current of Zn is lower than the other two metals and among these three metals zinc has passivation behaviour. Corrosion behaviours of binary alloys (Cu-Zn, Cu-Sn and Zn-Sn) and ternary Cu-Zn-Sn were examined. Generally, corrosion resistivity of binary alloys on Pt is higher than that of metals on Pt. It could be said that Zn dominates corrosion current of alloys deposited from a deep eutectic solvent. Corrosion resistivity of binary alloys on steel is close to each other. Corrosion current density of binary alloys on Pt is approximately 10 times more resistive than bare steel. The polarisation curve of the ternary alloy of Corrosion resistivity of ternary alloy (Cu-Zn-Sn) on Pt is eight times greater than bare steel. Alloys could be electrodeposited on steel to prevent corrosion.