Processing of Zirconium Oxide Raw Materials to Produce Zirconium Silicides via Electrolysis of KCl-K₂SiF₆-ZrO₂ Melt

The possibility of electrochemical synthesis of zirconium silicides by electrolysis of KCl-K 2 SiF 6 melt with ZrO 2 additives at 790 °C has been studied. To determine the synthesis parameters, the kinetics and some features of the mechanism of the cathodic process in the investigated melt on glassy carbon were studied by cyclic chronovoltammetry and chronoamperometry. It was shown that the electroreduction of silicon ions in the KCl-K 2 SiF 6 melt takes place at potentials from 0 to −0.2 V. Additional peaks at more negative potentials were obtained on the voltametric dependences, presumably related to the reduction of zirconium ions and the co-reduction of silicon and zirconium ions. Electrolysis of KCl-K 2 SiF 6 melt with additions of 0.33 and 0.66 wt% ZrO 2 in galvanostatic mode at cathodic current density of 20 mA cm −2 was performed in order to check assumptions. Cathode deposits were obtained, which were analyzed by X-ray diffraction and scanning electron microscopy after separation of salt residues. It is shown that the precipitates were represented by zirconium silicides (ZrSi 2 , ZrSi) as well as oxides (SiO 2 , ZrO 2 ).