Influence of the Application of Direct Current on the Wetting of Graphite by Halides of Metals of the First and Second Groups

Abstract

The present investigation was carried out with the object of determining the character of the adsorption of anions and cations on the molten salt-graphite interface with anodic and cathodic polarization of a graphite support. Previous investigations on the influence of the application of current on the wetting of graphite by cryolite and cryolite-alumina melts [1, 2] resulted in the tentative conclusion that the variation in the surface properties of the boundary layers when under current was affected not only by the character of the bond between the anions and cations, but also by the value of the potentials or the position occupied by the anions and cations in the voltage series in the respective salt media. In the investigation of multicomponent systems like NaF-Na₃AlF₆. AlF₃-Na₃AlF₆, and also these systems in the presence of alumina and different salt additions, the conclusion was reached, as a first approximation, that the more electropositve cations were the most surface active on the boundary with the cathode, and the most electronegative anions were the most surface active at the boundary with the anode. These investigations, however, did not clarify the influence of the different cations on the adsorption of anions with anodic polarization, nor the influence of anions on the adsorption of cations with cathodic polarization.