Direct selective extraction of titanium silicide Ti_5Si_3 from multi-component Ti-bearing compounds in molten salt by an electrochemical process

摘要

Titanium silicide (Ti_5Si_3) 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 CaCl_2 system at 950-1050℃ 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. Ti_5Si_3 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 Ti_5Si_3 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℃ 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 Ti_5Si_3 is confirmed.