Deposition and Dissolution on Sinusoidal Electrodes

Abstract

Deposition and dissolution have been simulated on model sinusoidal electrodes. The effects of variations in kinetic, geometric, and mass transport parameters were studied. Predicted reduction in the amplitude of a profile undergoing anodic dissolution is compared with results obtained from other approximate solutions. Simulated deposits on macroprofiles, where mass transport limitations are important, displayed a characteristic flattening at the peak. The flattening is not manifested on microprofiles, where the diffusion layer is assumed to follow the average surface plane of the sine wave. Simulations at low Wagner numbers predicted that a slight depression should form at the peak of the sine wave during deposition for a specified range of geometric parameters. The phenomenon, which was unexpected from a prioriconsiderations, is shown to result from an interaction between the effects of ohmic drop, surface overpotential, and of electrode curvature. Contours of copper deposits, for comparison with simulated deposit profiles, were obtained on initially sinusoidal mandrels. In order to perform experiments over a range of Wagner numbers, sinusoidal profiles of different initial amplitudes (0.3 and 2 mm) were machined on the mandrels. Based on the deposit thickness (∼1 mm) at each point, deviation between simulated and experimental results is less than 13%.