Author(s)

A. Powell & W. Pongsaksawad

Abstract

A new phase field model is presented for simulation of phase boundary motion due to transport-limited electrochemical reactions. The model consists of Cahn- Hilliard diffusion based on a statement of free energy with an electrostatic energy term, and conservation of charge. It is shown that under assumptions of negligible charge transfer resistance (mass transfer dominance) and rapid charge redistribution, the conservation of charge equation reduces to zero divergence of current density. When simulating electrolytic metal oxidation/reduction with an unsupported electrolyte, the model reproduces analytical models of cathode interface stability. It can also simulate electronically mediated reactions at separate interfaces, such as those occurring in metallothermic reduction processes. Results are presented for both unsupported and supported electrolytes, and both solidstate transformations and those involving fluid flow, including fluid-structure interactions using the Mixed Stress model for diffuse interface fluid-structure modeling. Keywords: electrochemistry, mathematical modeling, phase field, fluid flow, stability analysis, dendrite, streamer, titanium, steelmaking. 1 Introduction Electrolysis enjoys widespread use for extraction of metals from their ores or aqueous solutions. However, metal electrodeposition very often results in a rough surface or dendrites due to a Mullins-Sekerka instability at the cathode/electrolyte

Keywords

electrochemistry, mathematical modeling, phase field, fluid flow,stability analysis, dendrite, streamer, titanium, steelmaking.