Model of Electrodeposition Stability - Surface Evolution at a Planar Electrode

摘要

Electrodeposition interfacial phenomena draw attention for scientific interest and for various applications. A common objective is the control of surface feature development from an initially planar or smooth electrode. In some situations, growth is desirable such as the micro- and nano-structures illustrated by Budevski et al. (1). Conditions were discovered to generate nano-scale pyramids on an Ag (100) surface. In other cases, prevention of growth is desired, such as dendritic formations during a steelmaking electrodeposition process (2). Motivation for the present work draws from this latter application. A high temperature (e.g., 1400 ℃) steelmaking process involves a cathodic reduction of molten FeO electrolyte to pure Fe metal. The application of DC current can increase the steel production rate by several factors. However, the formation of protrusions on the surface causes short circuiting dendrites, and thus loss of Faradaic efficiency and potentially system failure. Hence, it is desirable to ascertain conditions to maximize the rate of deposition (lowering processing costs) while maintaining dynamically stable uniform growth. Dussault and Powell(3,4) and Pongsaksawad et al.(5,6) developed a phase field model on which the present work is based. However, steady-state profiles were not analyzed, and the dynamic stability analysis only evaluated growth seeded by specific spatial disturbances.