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Zn-SiC nanocomposite coatings are successfully produced by galvanostatic electrodeposition from aqueous citrate solutions, using SiC nanoparticles (NPs) with an average size of 56 nm. The optimal parameters of the zinc-citrate bath are chosen on the basis of analysis of a thermodynamic model. The effect of applied current density, bath composition, and hydrodynamic conditions are studied. The kinetics and mechanism of zinc reduction in the presence of SiC NPs are investigated using cyclic voltammetry. The surface charge of SiC NPs suspended in the electrolyte solutions is examined by the dynamic light scattering technique. The electrodeposited Zn-SiC coatings are characterized by wavelength dispersive X-ray fluorescence and scanning electron microscopy. It is shown that SiC codeposition with Zn proceeds through the entrapment of ceramic NPs during the reduction of citrate-zinc ions that are first adsorbed on the surface of the ceramic NPs. A maximal content of 6.4 wt% SiC incorporated into the Zn matrix is obtained at the lowest applied current density of j =-0.5 A dm-2 , with a nearly constant faradaic efficiency of 90%.

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A comparison is made between the codeposition behavior of Zn with SiC nanoparticles (NPs) of two average sizes: 56 nm and 90 nm. The SiC NPs are first characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Dynamic light scattering (DLS) is used to compare the surface charge of both kinds of SiC NPs suspended in aqueous citrate electrolytes. The effect of applied current density, hydrodynamic conditions, and total charge passed on the SiC content in the coating and electrodeposition rate is studied. The electrodeposited Zn-SiC coatings are characterized by wavelength dispersive X-ray fluorescence (WDXRF), scanning electron microscopy (SEM), and XRD. The results obtained confirm that Cit-Zn complexes are adsorbed on the surface of the SiC NPs, which are transported to the cathode and are codeposited with Zn during reduction. Zn-SiC incorporation may proceed also by mechanical entrapment of SiC agglomerates in the cavities and pores that are formed in the deposit under condition of relatively fast Zn deposition, which is accompanied by fast hydrogen evolution.