海绵钛熔盐电解制取高纯钛粉过程中离子价态、杂质及电结晶行为

摘要

以 NaCl-KCl-TiClx为电解质，以海绵钛为原料进行熔盐电解提纯制取高纯钛粉。研究电解过程中离子价态、纯度及电结晶的演变规律。XPS 分析表明，在电解前期、中期及后期，钛离子主要分别以+4、+3、+2价存在。在电解过程中，Si、Cr、Mn、Al 杂质的含量基本恒定，而 Fe、Cu、Ni 杂质的含量逐渐降低，O、N、H元素的含量明显增加。在电解钛粉体内部，杂质元素主要分布在枝晶间所形成的“坑道”内。电解钛粉体形貌及粉体粒度受电解温度和时间的影响较大，温度升高及时间延长可增加钛粉体的粒度。透射电镜分析表明，电结晶的钛粉体不是单晶，而是由大量的纳米晶粒及亚晶粒组成的，晶粒尺度为100~500 nm。对电解机理进行了讨论。%High-purity titanium powder was prepared by molten salt electrorefining from sponge titanium in NaCl-KCl-TiClx salts. The titanium valence, purity and electrocrystallization during electrolysis process were studied. The XPS analysis showed that the titanium valences are mainly +4, +3 and +2 at the earlier, medium and later stages of electrolysis, respectively. During the electrolysis process, the contents of impurities Si, Cr, Mn, Al vary little, and the contents of impurities Fe, Cu, Ni decrease markedly, while the contents of impurities O, N, H increase obviously. The residual impurities are usually distributed in small tunnel of dendritic crystals. Enhancing the electrolysis temperature and prolonging the electrolysis time can increase the titanium particle size. The TEM analysis showed that the electrodeposited titanium is not a single crystal, but contains many nanostructured grains and subgrains, with grain size of 100-500 nm. The electrolysis mechanisms were also discussed.