ELECTROCHEMICAL CORROSION EVALUATION OF SnSb ELECTRODEPOSITED COATINGS

Abstract

Sn_xSb_(1-x) coatings were electrodeposited from 1ChCl:2EG on copper. The corrosion resistance of the electrodeposits was evaluated in 0.1 mol dm^-3 of NaCl. The characterization was performed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Voltammetric profiles showed that the electrodeposition potential shifted towards less positive values with increasing Sb³⁺ concentration. SEM images revealed that the coatings exhibited grains and clusters. EDS analyses showed that the Sb content increased with the Sb³⁺ concentration. XRD results indicated the formation of the SbSn phases such as Cu₂Sb, Cu₆Sn₅, and Cu₆(Sn,Sb)₅. The potentiodynamic polarization (PP) curves showed that Sn and Sn₇₇Sb₂₃ presented a passive potential region, while Sn₃₇Sb₆₃ had an active dissolution in the electrolyte. Immersion tests were performed for 24 h and XRD results revealed Cu, Sn, SnO, SbSn and Sb₂O₄ phases. Considering 48 h, Cu, CuSn, SnO₂ and SnSb phases were identified. The polarization resistance values of 4.60, 14.69 and 1.81 kΩ cm² were achieved for Sn, Sn₇₇Sb₂₃, and Sn₃₇Sb₆₃, respectively. The EIS results suggested that adding Sb³⁺ improves corrosion resistance for SnSb samples with higher Sn content. For Sn₇₇Sb₂₃, the charge transfer resistance was 10.5 kΩ cm², for Sn and Sn₃₇Sb₆₃ 1.15 and 1.46 kΩ cm², respectively.

Keywords:
Sn_xSb(_1-x) coatings; electrodeposition; deep eutectic solvent; corrosion