The Effect of Direct and Pulsed Current in the Presence of Surfactants on the Electrodeposition of Zn–SiC Nanocomposite Coatings

Zn-SiC nanocomposite coatings were electrodeposited from aqueous citrate electrolytes using either direct current deposition (DCD) or pulsed electrodeposition (PED). The effects of various surface-active organic compounds (SDS, gum arabic, gelatin, CTAB, PEG 20000, and Triton X-100) on the coatings' surface morphology and chemical composition were studied. The influence of pulse frequency and duty cycle on the percentage of the SiC nanoparticles (NPs) incorporated and on the quality of the deposits was also investigated. The amount of SiC NPs incorporated in the Zn matrix was similar for layers obtained by DCD compared to PED. The Zn-SiC coating deposited by PED exhibited a more fine-grained surface morphology. The percentage of SiC co-deposited with Zn was mainly affected by the type of surfactant used. The ionic surfactants (cationic gelatin and CTAB or anionic gum arabic) allowed the co-deposition of considerably higher amounts of SiC NPs with Zn, compared to the non-ionic compounds PEG 20000 and Triton X-100. However, the use of high molecular weight organic compounds such as gelatin and gum arabic led to aggregation of SiC NPs within the Zn matrix.