Sono-Electroplating of Cu-Ni Alloy Thin Films and their Corrosion Behavior

Abstract

The proposed work is the development and optimization of electroplated/sono-electroplated CuNi alloy thin films with varying electrolyte bath concentration, applied potential, and its effect on the thin films properties and also to study the corrosion behavior of the film. In current study CuNi alloy thin film were electroplated from an electrolytic bath containing 0.75M NiSO4.6H2O, 0.195M H3BO3 and different concentration of CuSO4.5H2O (0.075M, 0.05M, and 0.0375) in order to obtain Cu-Ni molar concentration ratio of 1:10, 1:15, 1:20 respectively, at a current density of 30 mA/cm2 . A stainless steel circular bar with an exposed area of 0.5cm2 and a 5 cm long platinum rod of 0.2 cm diameter served as cathode and anode respectively. Depositions were carried out by varying the temperature (25º±2ºC) and bath concentration both in presence and absence of sonication. The synthesized thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and surface profiler. XRD analysis confirmed that alloy formation was better in presence of ultrasound. SEM and EDS both surface morphology and composition of the thin film showed a strong dependence on the bath condition (silent and sonication), bath concentration and temperature. Residual stress analysis showed that a decrease in stress, increase in roughness and film thickness in presence of sonication bath. Corrosion behavior of films studied by using potentiostat with three electrodes setup which revealed that thin film synthesized under silent condition had better corrosion protective behavior as compared to films in ultrasonic condition. Electrochemical impedance spectroscopy (EIS) technology has used for affirming electrochemical reaction and provided more information about corrosion at the electrode/electrolyte interface.