A ZINC-NICKEL ALLOY ELECTRODEPOSITION KINETICS MODEL FROM THICKNESS AND COMPOSITION MEASUREMENTS ON THE ROTATING-DISK ELECTRODE

Measurements of radial variations of composition and thickness of electrodeposited zinc-nickel alloys on a rotating disk electrode were made for deposits obtained at steady state from chloride electrolytes at different bath compositions, electrode rotation rates, and applied voltages. A two-dimensional transport model, which accounts for migration and complexation of the zinc by chloride, was used to calculate the radially dependent interfacial concentration and potential profiles for each set of experimental conditions. The calculated profiles and the experimental data were compared to estimate the unknown parameters in a postulated electrode kinetics model for the codeposition process. Parameter estimation was first conducted using the data from individual experiments, and the data from several experiments were then grouped together to provide a global estimation of the parameters. The match between model and data was very good for secondary current distribution conditions, and became less reliable under strong mass transport control. The kinetics model identified here can be used in constructing models that predict nickel-zinc alloy deposit composition and thickness distribution in cells of any geometry. © 1990, The Electrochemical Society, Inc. All rights reserved.