Discussion aspects of the theory of galvanostatic phase formation

Abstract

The thermodynamic and kinetic peculiarities of metal nucleation under galvanostatic conditions are considered. The alternative expressions for supersaturation in electrochemical systems in terms of overall overpotential (Kaischew, Budevski, Malev, Polukarov, de Levi at al.) or crystallization overpotential (Fischer, Volmer, Schottky, Vetter, Lorenz, Gerischer at al.) are discussed. It is shown that incorrect use of expression for supersaturation in terms of overall overpotential leads some authors to unreasonable interpretation of experimental data. This leads to negative impact on  electrochemical nucleation theory development. Some kinetic theories (Schottky, Baraboshkin, Kashchiev) take into account changes of supersaturation and atoms consumption by growing nuclei during the current pulse. However this corrections are difficult to identify. Computer modeling of galvanostatic phase formation (Isaev, Baraboshkin, Volegov) correctly describes the time dependence of the main parameters of nucleation. Moreover, applying of this approach in data processing of experimental overpotential transients requires the kinetic and thermodynamic constants of the process determination. Gutsov`s kinetic model is still more suitable for the analysis of experimental overpotential transients, because this theory takes into account the influence of crystallization overpotential on the rate of phase formation.