Stepwise decreasing current modes. I. Electrodeposition of metals from a bath with insoluble anode and limited volume of solution

A model of the stepwise decreasing current mode of electrodeposition of metals has been developed and checked with experiments. The electrodeposition of copper has been used for this purpose. It has been shown that the deposition time in the stepwise decreasing current mode, for sufficiently high step number, becomes close to that potentiotiostatic deposition.Nomenclature C concentration - C₀ initial concentration - D diffusion coefficient - F Faraday constant - i integer - I current - I₀ initial limiting diffusion current - k integer - m number - n number - Q quantity of electricity - S electrode surface area - t time - t_k^* deposition time fork current steps - t^* lim_kt_k^* - t_m deposition time required to decrease concentration from (m + 0.1)C₀ tomC₀ byI=mI₀ - t_n deposition time required to decrease concentration fromC₀ tonC₀ byI =nI₀ - U cell voltage - V volume of solution - z number of electrons - thickness of the diffusion layer - defined by Equation 3