Simulation of Localized Electrodeposition of Microwires and Microtubes

Abstract

Localized electrodeposition is an additive manufacturing method for fabricating three-dimensional microstructures with precise control over process conditions and geometry of deposit. This technique has been widely used in the last two decades, because it makes possible to form various types of microstructures using no complex and expensive equipment. The rate of deposit growth, its dimensions and morphology depend on a large number of factors. A discrepancy between the deposit growth rate and the velocity of moving anode is of critical importance: if the deposition rate is higher than the anode velocity, the interelectrode gap decreases up to a short circuit; if the deposition rate is lower than the anode velocity, the interelectrode gap increases, the deposit ceases to grow, and, eventually, it becomes impossible to obtain a microstructure with a high aspect ratio. Along with the anode velocity, the interelectrode gap also has a strong effect on the deposit shape and dimensions. In several works, it was shown that different structures, such as microwires and microtubes, can be formed. However, the regularities of the process have not been adequately studied.This work is devoted to the simulation of localized electrodeposition with moving ring-shaped microanode. The Laplace equation for the potential in the solution and the equation for cathode surface evolution are used as the mathematic model. The kinetics of electrode reaction of metal deposition is taken into consideration by the Butler-Volmer equation. To provide the production of microwires and microtubes with a high aspect ratio, the anode rate was taken to be equal to the highest local rate of deposit growth. The effect of process parameters and microanode geometry on the deposit shape and dimensions is theoretically studied.