Controlled Electrochemical Synthesis of Dense Titanium Powder from TiO2 in Fluoride-Based Molten Salts: Dissolution Behavior, Kinetics, and Particle Evolution

This study investigated the effect of TiO 2 dissolution behavior in NaF–K 2 TiF 6 molten salts and subsequent electrolysis on the production of dense titanium powder. Under isothermal saturation conditions at molar ratios of 1.3–1.9 and temperatures of 800°C–890°C, TiO 2 solubility increased with temperature, reaching 9.75 wt% at 890°C and a 1.3 molar ratio. Dissolution kinetics revealed a two-stage process: an initial zero-order reaction during the first 5 min, followed by a first-order reaction for approximately 90 min. The dissolved TiO 2 formed TiOF n 2−n complexes, leading to K 2 NaTiOF 5 precipitation. Higher saturation of TiOF n 2−n resulted in finer particles, while lower saturation promoted the formation of coarser particles. Electrolysis experiments were conducted at 800°C with a NaF–K 2 TiF 6 molar ratio of 1.3:1. The results revealed that an increase in cathode current density reduced both the specific surface area and oxygen content of the titanium powder. At cathode and anode current densities of 1.9 and 0.31 A/cm 2 , dense spherical titanium powder with 0.22 wt% oxygen was obtained after 4 h of electrolysis. These findings confirm the feasibility of producing dense titanium powder via fluoride-based molten salt electrolysis.