A Study on the Anode Effect in KF-2HF System. III. Influence of Bath Temperature and Surface Tension and Addition of Fluoride Particles on the Occurrence of the Anode Effect

Abstract

Abstract The decomposition reaction of the graphite fluoride film formed on the edge plane of pyrolytic graphite, carbon, and graphite electrodes was faster in a KF·HF bath (250 °C) than in a KF·2HF bath (100 °C) due to the higher temperature of KF·HF bath. The critical current densities (CCD’s) were about 0.1 A/cm2 for the layer and edge planes of pyrolytic graphite, carbon, and graphite electrodes in the KF·HF bath, and the CCD for each electrode was larger in the KF·HF bath than in the KF·2HF bath. The anode effect took place easily on the glassy carbon electrode in the KF·2HF bath. However, the anode effect did not take place in liquid hydrogen fluoride due to its very low surface tension, although the graphite fluoride film was formed on the electrode surface. The zeta-potential of aluminum fluoride particles in liquid hydrogen fluoride containing 0–20 mol of potassium fluoride/1 and that of magnesium fluoride particles in liquid hydrogen fluoride were almost zero at 0 °C. From the results it is not proper that the effect of the addition of dispersed particles upon the anode effect is explained by the view of electrostatic force of the particles proposed so far.