摘要:
对熔盐电解提钛工艺中钛离子的电化学沉积行为进行研究, 首先通过调整TiCl4和海绵钛的比例在NaClKCl熔盐中反应制备出不同电解质组分, 然后在制备的电解质体系中研究钛离子的电化学沉积行为。低价钛电解质组分的XRD分析结果表明, 在993 K的NaCl-KCl熔盐中, 当TiCl4与Ti摩尔比为1∶2时, 反应产物主要为2价的TiCl2, 电解质形成NaCl-KCl-TiCl2体系;当摩尔比为2∶1时, 反应产物主要为2.57价的TiCl2和K3TiCl6, 电解质形成NaCl-KCl-TiCl2-K3TiCl6体系。两种电解质体系的循环伏安研究结果表明, NaCl-KCl-TiCl2体系中钛离子的还原历程为Ti2+→Ti, 主要受扩散影响, 扩散系数为2.93×10-5cm2/s, 而NaCl-KCl-TiCl2-K2TiCl6体系中钛离子还原历程为Ti3+→Ti2+和Ti2+→Ti两步。钛离子电化学沉积产物的SEM分析结果表明在NaCl-KCl-TiCl2体系中, 得到的钛粉产物呈现大颗粒的枝晶状, 随着电流密度增大和钛离子浓度减小, 钛粉产物颗粒逐步变细;而在NaCl-KCl-TiCl2-K2TiCl6体系中获得产物为细颗粒的多孔状钛粉。
Abstract:
The electrochemical deposition behaviors of titanium ions in titanium extraction by molten salts electrolysis were investigated.Different electrolytes were firstly prepared by adjusting the ratio of TiCl4 to titanium sponge in NaCl-KCl melts then the electrochemical deposition behaviors of titanium ions were analyzed in the obtained electrolyte systems. According to XRD of the electrolytes of low valence titanium,the main products were TiCl2 and NaCl-KCl-TiCl2 electrolyte system can be formed when the mole ratio of TiCl4 to Ti was 1:2 at 993 K in NaCl-KCl melts,while the TiCl2 and K3TiCl6 with 2.57 of average valence and NaCl-KCl-TiCl2-K3TiCl6 electrolyte system were obtained when the mole ratio of TiCl4 to Ti was 2:1.The results of cyclic voltammetry for the electrolyte systems mentioned above indicated that the reduction course of titanium ions was Ti2+→Ti in NaCl-KCl-TiCl2 influenced by diffusion with 2.93 × 10-5cm2/s of diffusion coefficient and it was two steps of Ti3+→Ti2+and Ti2+→Ti in NaCl-KCl-TiCl2-K2TiCl6 system.The morphology of titanium powder obtained in NaCl-KCl-TiCl2 system was dendrite large particles,and with increase of current density and decrease in concentration of titanium ions the particle size of products decreased.Fine and porous titanium powder was prepared in NaCl-KCl-TiCl2-K2TiCl6 melts.
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