Direct selective extraction of titanium silicide Ti5Si3 from multi-component Ti-bearing compounds in molten salt by an electrochemical process

Titanium silicide (Ti5Si3) has been extracted directly from complex Ti-bearing compounds by electro-deoxidation. A pressed cylindrical pellet of the multi-component compounds acted as a cathode, and carbon-saturated liquid metal contained in a solid-oxide oxygen-ion-conducting membrane (SOM) tube served as an anode. This electrochemical process was carried out in a molten CaCl2 system at 950–1050 °C and 3.5–4.0 V. The parameters of electrolysis and the electrolytic characteristics were investigated, and the morphology and phase composition of the final products were examined. Ti5Si3 was directly extracted from Ti-bearing compounds. Electrolysis time, applied potential, and electrolysis temperature are the dominant factors that affect the characteristics of the final products. The mechanisms of the extraction of Ti5Si3 and the removal of metallic elements (Ca, Mg, and Al) are suggested based on our experimental results and theoretical analysis. The optimal conditions of the electrolysis are a temperature of ∼1050 °C and a potential of 3.5–4.0 V, which result in rapid reduction and good product morphology. The excellent oxidation resistance of the extracted Ti5Si3 is confirmed.

► Ti5Si3 has been successfully extracted from multi-component Ti-bearing compounds.
► The multi-step mechanism of the electrochemical extraction process is proposed.
► The excellent oxidation resistance property of the obtained Ti5Si3 is confirmed.