The electrodeposition of zinc-nickel alloys from sulphate bath has been studied using cyclic voltammetry technique, where some characteristics have been followed during both of the deposition and the dissolution of the alloys. Under the examined conditions, electrochemical and surface analysis indicate that the deposition has taken place with the formation of two structures have a composition corresponding to γ and δ phases of zinc-nickel alloy. Corrosion properties of Zn-Ni have been studied depending on the light of anodic linear polarization resistance technique. It is found that the protective capability of galvanic deposits containing Ni is substantially higher than that of ordinary Zn deposits. The effect of current density and sodium sulphate and boric acid concentrations on the morphology and the composition of the deposited films have been also studied. The results indicate that the deposition potential, morphology and the composition of the deposit have been greatly influenced by the current density. The Ni content in the deposition layer has been depressed at high current density, whereas, Zn deposition has been predominant. The increase of sodium sulphate in the bath significantly has increased the amount and content of Ni in the deposit and has decreased those of Zn. The addition of boric acid to the plating bath has increased the nucleation density of the deposit and consequently the content of Zn in the alloy. This effect has been attributed to the adsorptive interactions of boric acid at the electrode surface.
M.M. Abou-Krisha , A.M. Zaky and A.A. Toghan , 2006. Morphology, Composition and Corrosion Properties of Electrodeposited Zn-Ni Alloys from Sulphate Electrolytes. Asian Journal of Biochemistry, 1: 84-97.