Development of a Quantitative and Predictive Model for Electrodeposition of Metals and Alloys with Experimental Verifications

Abstract

Electrodeposition is widely used in the refinery, manufacture, and coating of metals and alloys. Electrodeposition is a complicated process with many factors, such as deposition potential, current density, electrolyte composition and concentration, convection, additives, and temperature, can have significant impacts on the phase composition, morphology, and particle size of the deposited metals/alloys, thus consequentially impacting the physical and chemical properties of the deposited parts. In the past, a recipe for a particular metal/alloy electrodeposition is commonly established through trial-and-error tests, which is very time consuming. Here we report our recent efforts trying to build a quantitative and predictive model based on ex situ and in situ experimental characterizations of electrodeposition processes.To build the model, we chose copper as the model material for electrodeposition. A few electrochemical cells which have different geometries and dimensions and provide non-uniform current density distributions were designed and used. Through variation of the electrode placement and cell geometry, the current density distribution on the working electrode in the electrodeposition process can be tuned. The amount and growth rate of the deposited Cu layer in various electrochemical cells and under different deposition conditions (such as different potential, electrolyte concentration or physical location) were experimentally measured with using carefully calibrated and normalized X-ray diffraction (XRD) data. A multi-physics multi-scale model was developed to quantify the distribution of the current density and the growth rate of deposited Cu at different locations. The experimentally measured data was used to verify and improve the model. The results showed that the model can accurately predict the distribution of the current density with given nominal deposition potential or current, and thus predict the growth rate of the deposited Cu phase.The success of this model offers hopes to rationally design the deposition of metals and alloys to replace conventional trial-and-error method. The impact of different deposition substrates, additives, electrolyte concentrations will also be discussed. Proof-of-concept experiments also demonstrated that this rational design method can be applied to the design of electrodeposition of alloys, offering a much broader range of potential applications.