| Mathematical analysis of the electrodeposition process of nickel-chrome (Ni-Cr) and nickel-chrome-phosphorus (Ni-Cr-P) on the rotating disk and rotating cylinder electrodes shows that experimental observations can be rationalized by a model which takes into account the solution chemistry, mass transport through the diffusion layer, and the surface electrochemical reactions. A theoretical analysis shows that pulse plating improves the selectivity for chromium in a Ni-Cr alloy and increases the current efficiency (i.e., reduces the unwanted hydrogen evolution). Pore free, high corrosion resistant Ni-Cr-P alloys were successfully deposited on copper cylinders. Alloy compositions can be adjusted by controlling the applied currents.; Salient features as to the effect of homogeneous chemical reactions within the diffusion layer, and the importance of considering ionic activities were also explored in a simple Br{dollar}sp-{dollar}/Br{dollar}sb2{dollar} system because of its relevance to actual electroplating problems. Results show the consideration of chemical reactions is very important, while in most plating conditions the correction of the activity coefficients is not critical. |
