A study on the effect of inter-electrode gap and pulse voltage on current density in electrochemical additive manufacturing

Electrochemical Additive Manufacturing—a novel non-thermal metal additive manufacturing process offers some advantages over traditional energy beam-based layered manufacturing processes, which have several inherent limitations such as thermal damages, residual stress, and part size restrictions. In this process, the principle of localized electrochemical deposition of metals is combined with the additive manufacturing procedure to manufacture metal parts at room temperature directly from computer-aided design files. The focus of research work presented in this paper is on the modeling of the current density produced in the electrochemical deposition system based on the Fick’s law of diffusion and electrode kinetics using the Butler–Volmer equation. The current densities involved in the micro-electrochemical additive manufacturing on nickel have been found to be several orders of magnitude higher than the standard electroplating studies, making it a very high overpotential deposition. The model developed in this work was used to study the effects of applied potential, pulse duty cycle, inter-electrode gap, and concentration on the current density and the transient diffusion layer thickness. The model predicted that lower inter-electrode gaps facilitated higher current density leading to faster deposition rates. The pulse voltage was found to produce higher current densities during the pulse-on time. The modeled current density values were validated with experimental results using the in-house-built electrochemical additive manufacturing setup.