Electrosynthesis of Ti₂CO_nfrom TiO₂/C Composite in Molten CaCl₂: Effect of Electrolysis Voltage and Duration

Abstract

Ti2COn powders with controllable oxygen contents have been successfully synthesized by electro-reduction of solid TiO2-graphite composite precursors in molten CaCl2. The effect of electrolysis time and applied cell voltage on the carbon and oxygen content of the product was systematically investigated. The reduction pathway of the composite electrode was studied based on the analysis of intermediate products using X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is suggested that the reduction starts with converting TiO2 and graphite to CaTiO3 and Ti2COn. The resulting CaTiO3 is then reduced to CaTi2O4 which is subsequently reduced to Ti2COn. The present graphite significantly accelerates the electro-reduction of TiO2. The oxygen content decreases with increasing the electrolysis cell voltage and prolonging the electrolysis time. It is found that the cell voltage and electrolysis duration should be strictly controlled to avoid oxygen-depletion in the final product. The obtained product shows good electronic conductivity at room temperature. This process exhibits a relatively high current efficiency for production of Ti2COn from TiO2-graphite composite.

Molten Salt Electrochemical Synthesis of Ternary Carbide Ti3AlC2 from Titanium‐Rich Slag

“…The curve reveals that the current decreases rapidly within the initial 2 h and then declines slowly to a stable level (around 0.45 A) until the electrolysis is terminated. Electrodeoxidation generally occurs from the outside to the inside of the cathodic pellet, and the preferentially generated products, such as TiC x O y , may accelerate the reduction due to their good conductivities . As the reaction proceeds and the removal of oxygen ions continues, the reduction speed of the pellet becomes slower and the current is relatively stable during the later electrolysis period (10–20 h).…”

“…Electrodeoxidation generally occurs from the outside to the inside of the cathodic pellet, and the preferentially generated products, such as TiC x O y , may accelerate the reduction due to their good conductivities. [39,40] As the reaction proceeds and the removal of oxygen ions continues, the reduction speed of the pellet becomes slower and the current is relatively stable during the later electrolysis period (10-20 h). After 20 h electrolysis, the total charge flowing through the electrolytic cell is %9.56 Ah.…”

Molten salts and energy related materials

“…This can be a disadvantage if rening is required but can be a considerable advantage if alloys are desired especially those that are difficult to make when the melting point of one element is greater than the boiling point of some of the other alloying elements. A very large number of alloys and intermetallic compounds have been made including TiNi, [45][46][47] TiMo, 48 TiW, 49 Al 3 Sc, 50 NbAl, 51 NiTiHf, 52 TaNb, 53 NbHf, 54 HfC, 55 Ti 2 CO, 56 TiSi, 57 LaNiCo, 58 TaC 59 and TiC/SiC composite. 60 At the present time, the process is being developed by Metalysis Ltd (http:// www.metalysis.com) in the UK concentrating on tantalum powder for capacitors and titanium powders for near net shape processing.…”

In-situ synthesis of zirconium oxycarbide by electroreduction of ZrO2/C in molten salt

“…Molten salt electrolysis provides a convenient and fairly easy way to obtain carbide materials. It was reported that MCxOy and MCx have been synthesized by electrolysis using the mixture of MO2 and C as precursor in molten chloride [19,[21][22][23][24][25][26]. Electrolytic synthesis of MCxOy is a process of removing O 2from MOx and carbon complexes.…”