NaF-K_(2)TiF_(6)-TiO_(2)体系中直接电解制备钛的可行性研究

Direct Electrolytic Preparation of Titanium in NaF-K_(2)TiF_(6)-TiO_(2) System

以NaF-K_(2)TiF_(6)作为熔盐电解质,TiO_(2)作为溶质,探究直接电解TiO_(2)制备金属钛的可行性.通过对比不同摩尔比NaF-K_(2)TiF_(6)的初晶温度和TiO_(2)溶解度以选择较为合适的熔盐体系,而后对该体系进行热力学计算、三电极体系循环伏安测试(Mo棒作为工作电极和参比电极,高纯石墨作为对电极)和180min的双电极恒流电解(不锈钢棒作为阴极,石墨作为阳极).结果表明,摩尔比为1.5∶1的NaF-K_(2)TiF_(6)体系可作为电解钛的电解质,TiO_(2)的溶解以化学形式溶解为主,其溶入形式以K_(2)NaTiOF_(5)为主,以Na_(2)Ti_(3)O_(7)为辅.且少量TiO_(2)溶解后会降低熔盐体系的初晶温度.T^(4+)的阴极过程分为两个阶段:TiF_(6)^(2-)/TiF_(6)^(3-);Ti^(3+)/Ti.热力学上钛的氧化物优先反应,二氧化钛的还原是逐级进行的.恒流电解阴极产物的钛以小颗粒形式存在并夹杂着一定程度的电解质.

The feasibility of directly electrolyzing TiO2 to prepare metallic titanium was explored, NaF-K2TiF6 being the molten salt electrolyte and TiO2 being the solute. A more suitable molten salt system was selected by comparing the primary crystal temperature and TiO2 solubility of NaF-K2TiF6 with different molar ratios. Then the system is subjected to thermodynamic calculations, three-electrode system cyclic voltammetry test(Mo rod as working electrode and reference electrode, high-purity graphite as counter electrode) and 180 min double-electrode constant current electrolysis(stainless steel rod as cathode, graphite As anode). The results show that the NaF-K2TiF6 system with a molar ratio of 1.5∶1 can be used as a molten salt electrolyte for electrolytic titanium. The dissolution of TiO2 is mainly in chemical form, and its integration form is K2NaTiOF5, supplemented by Na2Ti3O7. Moreover, the dissolution of a small amount of TiO2 can reduce the initial crystallization temperature of the molten salt system. The cathode process of T4+ is divided into two stages: TiF62-/TiF63- and Ti3+/Ti. Thermodynamically, the titanium oxide reacts preferentially, and the reduction of titanium dioxide is carried out step by step. The titanium produced by the constant current electrolysis cathode exists in the form of small particles and is mixed with a certain degree of electrolyte.