Role of buoyancy in the onset of dendritic growth in thin layer electrodeposition

Even in thin, quasi-two-dimensional horizontal cells, electrodeposition of treelike metal aggregates is accompanied by a gravity-induced fluid Row at the electrodes. This convective motion mixes the electrolyte and tends to h omogenize the concentration. This results in delaying the time at which the branched aggregates start growing, which roughly coincides with the Sand's time rat which the concentration goes to zero at the cathode. The relative influence of diffusion and convection on the concentration distributions d epends on cell thickness, salt concentration, and current density: dependin g on these parameters, we predict three different regimes for the onset of dendritic growth. We report here on the experimental observation of these r egimes. Our theoretical predictions quantitatively account for the observed behaviors. [S1063-651X(99)01703-1].