Production of Titanium Films via Segregation of Ce-Ti Alloy Coexisting with LiF-based Molten Salts

Abstract

Titanium (Ti) is widely desired in various industries because of its excellent properties. However, use of Ti is limited owing to the high costs associated with the extraction, melting, and rolling processes. In this study, we present a novel Ti film production process that does not require melting of Ti. To improve the practicality of the process, Ti films were formed through the reaction of Li₂TiF₆ with Ce and subsequent segregation in a Mo crucible. A Ti film with a thickness of 10 µm was obtained when 0.7 g of Li₂TiF₆ was added to 1.3 g of LiF molten salt on 8 g of liquid Ce in a Mo crucible, which reacted at 1000 °C for 9 h to form a Ce-Ti alloy. The alloy was maintained at 900 °C for 9 h to promote segregation. The thickness of the Ti film increased up to 90 µm when the segregation time was increased to 18 h, whereas an increase in the reaction time did not significantly affect the thickness of the Ti film. However, a decrease in the reaction time to 4.5 h inhibited the formation of the Ti film. When the Ce-Ti alloy with excess Ti at the bottom of the Mo crucible was segregated, a Ti film did not form on the Ce/molten salt interface. Furthermore, an increase in the amount of Li₂TiF₆ added to the molten LiF inhibited the formation of the Ti films as the Ce surface was covered with precipitates of CeO_xF_y. The mechanism of the formation of the Ti film via the segregation of the Ce-Ti alloy coexisting with LiF-based molten salts was explored based on these results.