Analysis of MHD effects on electrochemical processes: experimental and theoretical approach of the interfacial phenomena

摘要

Magnetically induced effects on electrolytic currents have been studied for various electrochemical systems. For all investigated cases, significant modification was found to be strictly relevant to transport process and magnetic effects were proved to be MHD (i.e. MagnetoHydroDynamic) phenomena. This holds for a reversible system (ferri-ferrocyanide) as well as for non reversible systems such as the electrocrystallization of Zn, or Ni from a pure or adulterated Watts bath. Assuming that the well-known magnetic effects on electrolytic currents in the bulk of solutions keep valid in the close vicinity of the electrode, the MHD phenomena are explained by taking into account the space charge of the diffuse layer. Theoretical expressions which depend on bulk composition and hydrodynamic conditions can thus be obtained. A comparison with experimental results under stationary or dynamic conditions was undertaken. For the latter case, two methods were employed: either classical electrochemical impedance spectroscopy (EIS) or MHD transfer function analysis. For both cases, a good agreement was found between expected physical values and calculated ones. Moreover, new results on electrocrystallization of Ni and Zn have been found.