| The focus of this research is the correlation of deposition procedure with alloy phase composition and morphology, and the correlation of phase composition with corrosion resistance. The electrodeposition of Ni-Zn alloy was studied to understand the interaction of alloy nucleation with kinetic and mass transfer processes.;Cyclic voltammetry of Ni-Zn deposition indicates that hydrogen adsorption and evolution are significantly involved in the formation of Ni-Zn alloy. Two forms of Ni-H alloy, ;The effect of pulse plating parameters was investigated on composition, morphology and phase composition of the alloy. Four effects which interact with each other were identified, the kinetic effect, mass transfer effect, inhibition effect and the effect of thermodynamic instability. By properly adjusting the pulse plating parameters, it has been demonstrated that, with equal average applied potential, pulse-plated alloy has higher nickel content than the constant-potential plated alloy. Pulse-plated Ni-Zn alloy shows also strong preferential orientation. Both the morphology and phase composition studies indicate that the time ratio of high potential period to low potential period is a very important parameter which controls the morphology and phase composition.;Finally, a preliminary corrosion study of Ni-Zn alloys was carried out. Based on a simple sacrificial-type corrosion mechanism applied to the zinc component, it can be explained why pulse-plated alloy has a higher corrosion resistance than the constant-potential plated alloy, as was found to be the case in a 3% aerated NaCl solution. However, the corrosion results need to be extended and the corrosion mechanism investigated more completely. |
