Effect of temperature on electronucleation and growth mechanism of Zn-Ni alloy in deep eutectic solvent

PurposeThe purpose of this paper is to study the effect of temperature on Zn-Ni alloys in ChCl-Urea. Design/methodology/approachBased on cyclic voltammetry experiments, the deposition behavior and kinetics of the Zn-Ni alloy are studied. The nucleation process of the Zn-Ni alloy is studied in detail via chronoamperometry experiments. The effects of the deposition temperature on the microstructure, Ni content and phase composition of Zn-Ni alloy coatings are investigated via scanning electron microscopy and X-ray diffraction (XRD) combined with classical thermodynamics. FindingsThe results show that with increasing temperature, the reduction peak shifts toward a more positive electric potential, which is beneficial for the co-electric deposition process, and the diffusion coefficient is estimated. With increasing temperature, the nucleation process of the Zn-Ni alloy becomes a three-dimensional instantaneous nucleation, the typical kinetic parameters are determined using the standard 3D growth proliferation control model and the Gibbs free energy is estimated. The Zn-Ni alloy coatings are prepared via normal co-deposition. With increasing temperature, the degree of crystallinity increases, the coating gradually becomes uniform and compact and the XRD peak intensity increases. Originality/valueThe nucleation process of the Zn-Ni alloy at different temperatures is analyzed. The diffusion coefficient D and Gibbs free energy are calculated. The contribution of the three processes at different temperatures is analyzed. The effect of temperature on the morphology of the Zn-Ni alloy coatings is studied.