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Abstract: The collective influence of crucial electrodeposition parameters (temperature, deposition voltage and bath composition) on the properties of Zn–Ni films electrodeposited in a choline chloride–urea eutectic-based ionic liquid was investigated. The microstructures, chemical compositions, phase structures and corrosion behaviors of electrodeposited films were analyzed using scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction and linear cyclic voltammetry, respectively. The surface morphologies and chemical compositions of the films were strongly dependent on the electrodeposition parameters. It was found that the amounts of nickel in the Zn–Ni alloy films were significantly higher than that present in the electrolytes and was always above 50%, indicating normal codeposition mechanism. Electrodeposition of high Zn content alloy is favorable at high electrodeposition voltages, high temperatures and high Zn (II)/Ni (II) ratios. Electrochemical measurements shows that under the conditions considered, the Zn–Ni film from 0.45M Zn (II)–0.05M Ni (II) deposited at 55°C and 0.8V exhibits the highest barrier corrosion resistance compared with the other films and this was attributed to a dense, smooth and crack free morphology with optimum Zn content. [Copyright &y& Elsevier]

Abstract: A comparative study was carried out on the deposition mechanism, microstructure, and corrosion resistance of Cu films electrodeposited from the base electrolyte of CuCl2·2H2O in a choline chloride–ethylene glycol eutectic solvent with absence and presence of the additive of ethylene diamine (EDA). The base electrolyte is unstable and produces rough Cu films with columnar grains. Upon the introduction of EDA, the modified electrolyte becomes stable and the nucleation of Cu deposits is strongly inhibited, thus producing a smooth and compact surface with finer grains. Uniform corrosion and decreased corrosion current density are recognized in the fine grained Cu films. [Copyright &y& Elsevier]

Abstract: Pure Ni and three Ni–Co alloys films, i.e. Ni–4wt.%Co, Ni–18wt.%Co, and Ni–40wt.%Co, are electrodeposited at room temperature from the choline chloride/ethylene glycol deep eutectic solvent dissolved by nickel or/and cobalt chlorides. Electrodeposition mechanism, microstructure, and corrosion properties of the films are investigated. Surface morphology and chemical composite of the films are significantly dependent on the Ni2+ and Co2+ concentrations in the electrolytes. Interestingly, it is found that the amount of cobalt in the Ni–Co alloy films is significantly lower than that present in the electrolytes, which indicates an absence of anomalous codeposition process for the non-aqueous electrolytes. However, anomalous codeposition of Ni–Co deposits is frequently observed for the aqueous electrolytes. The Ni–Co alloy films possess face-centered cubic structures and refined grains revealed by X-ray diffractometer and scanning electron microscope. Potentiodynamic polarization measurements show that the Ni film exhibits the noblest corrosion potential and the lowest corrosion current compared with the Ni–Co alloys films. Moreover, the more Co content the Ni–Co films have, the more negative corrosion potential and the higher corrosion current the films exhibit. [Copyright &y& Elsevier]

Abstract: A fully dense nanocrystalline (nc) Ni film on the brass substrate was fabricated by a simple electrodeposition from a choline chloride-based ionic liquid (choline chloride–ethylene glycol) at working voltage (between the two electrodes) of 1.0V and room temperature. It is found that the nc Ni with an average grain size of about 6nm has a face-centered cubic crystal structure. At the film/substrate interface, the epitaxial growth of some nc Ni grains on brass grains can be evidenced by the high resolution transmission electron microscope. The 6nm grain sized Ni exhibits a high strain rate sensitivity (m =0.051) and enhanced hardness values in the range of 7.6–9.7GPa. The deformation mechanism of the nc Ni under indentation is also discussed with the theoretical model fitting. The potentiodynamic polarization curve shows that the nc Ni film exhibits a much negative corrosion potential, which provides a sacrificial anode protection for the brass substrate. [Copyright &y& Elsevier]