Synthesis of Nickel Silicides during Electrolysis of the KCl–K2SiF6 Melt

Transition metal silicides are widely used in various fields of science and technology; available methods for their production are expensive and characterized by the relatively low productivity. In the present study, the possibility of synthesis of nickel silicides by electrolysis of the KCl–K2SiF6 melt at a temperature of 790°C is investigated. For this purpose, the melt electrolysis parameters are determined using a nickel cathode and cyclic voltammetry, and a series of experiments on the electrolysis of the melt under study are carried out in the galvanostatic mode at a cathode current density of 50 mA/cm2 and in the potentiostatic mode at a cathode potential of 0.15 to –0.15 V relative to a silicon quasi-reference electrode. The morphology and element composition of the deposits formed after separation of the electrolyte residues are studied by scanning electron microscopy and energy dispersive spectral analysis. As the cathodic overvoltage increases, the number of nuclei is shown to increase and, therefore, the deposit sizes decrease. The adhesion of the samples prepared during galvanostatic electrolysis is assumed to be poor. The voltammetry measurements performed at various potential sweep rates suggest that the electroreduction of silicon ions on nickel is irreversible and is accompanied by a chemical reaction.