| Abstract
| - A thin layer model is proposed to assist in the understanding of the electrochemical conversion of insulatorto conductor at the conductor/insulator/electrolyte three-phase interline (3PI) when the influence of massdiffusion in the electrolyte phase is negligible. The model predicts, under potentiostatic conditions, a linearvariation of the current or the length of the 3PI with time. When polarization is sufficiently large, the logarithmof the current/time ratio or the 3PI-length/time ratio, according to the model, increases linearly with theapplied potential. These predictions were tested against and agreed very well with two practical systems: theelectroreduction of solid AgCl to Ag in aqueous KCl and of solid SiO2 to Si in molten CaCl2. Kinetic parameterswere derived from experimental data using the model. Particularly, the electron transfer coefficient, α, wasfound to be about 0.29 for the reduction of AgCl to Ag in the aqueous KCl solution at room temperature butabout 10-2 for the reduction of SiO2 to Si in molten CaCl2 at 850 °C.
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