Numerical and experimental studies of Electrochemical Deposition quasi-stable growth

摘要

Electrochemical Deposition (ECD) in thin cells in a vertical position relative to gravity (cathode above anode) yields a growth pattern formation with a uniform front. However, detailed analysis of front evolution reveals a complex competition between neighboring branches leading to a locally fluctuating growth. We study these fluctuations through experiments and theory. Experiments reveal that the uniform dendrite front is due to an acceleration and deceleration of the leading branches, the latter resulting from the building of a stable stratified flow at their tips. Theory predicts local electrohydrodynamic fluctuations near the dendrite tips amid a global stable stratified flow. Dendrite tips are surrounded by arches joining neighboring tips, separating depleted and constant concentration solution zones; the arches shape is the result of electro and gravitoconvective driven vortex rings. The simulated growth of a single tip exhibits the formation of a mushroom-like shape which is consistent with experimental observations.