Study of the mechanical and structural properties of Zn-Ni-Co ternary alloy electroplating

Ternary zinc-nickel-cobalt alloys were electrodeposited on steel substrates from sulfate bath by direct current. Microstructural and mechanical properties of Zn-Ni-Co ternary alloy coatings were investigated and contrasted with the characteristics of Zn-Ni and Zn-Co alloy coatings. It was found that the obtained Zn-Ni-Co alloy exhibited more preferred surface morphology and mechanical properties as compared to the other alloy coatings electroplated at the same conditions. X-ray diffraction studies showed that the deposits of Zn-Ni-Co alloy coatings consisted of Zn, ZnNi3, and ZnCo13 phases. The structure, surface morphology, and surface topography of the deposited alloys were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray microanalysis (EDS), and atomic force microscopy (AFM). In addition, hardness, elasticity modulus, and adhesion strength of coated alloys were measured with dynamic ultra-microhardness (DUH) and Scratch tester.