Low-temperature electrodeposition of titanium in molten iodides
- PDF / 2,388,000 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 29 Downloads / 171 Views
RESEARCH ARTICLE
Low‑temperature electrodeposition of titanium in molten iodides Kazuhiro Kumamoto1 · Akihiro Kishimoto1 · Tetsuya Uda1 Received: 11 March 2020 / Accepted: 17 August 2020 © Springer Nature B.V. 2020
Abstract The LiI–KI–CsI ternary system has a eutectic point at 204 °C. In this study, the electrodeposition of Ti in eutectic LiI–KI–CsI at 300 °C and 250 °C was investigated. Firstly, the concentration of Ti2+ in the eutectic molten salt was measured at 300 °C under TiI2-saturated condition. We determined the concentration to be 0.18 mol% in cation ratio. After that, electrodeposition of Ti was demonstrated at 300 °C and 250 °C. The cathode and anode were Mo and Ti, respectively. At both temperatures, metallic Ti was obtained and confirmed by XRD. This result indicates for the first time that a new electrolytic process to produce bulk metal Ti below 300 °C is possible. Graphic abstract (a) Optical and (b) SEM images of electrodeposited Ti on Mo electrode after electrolysis in eutectic LiI–KI–CsI at 250 °C
Keywords Electrodeposition · Low temperature · Iodide · Molten salt
1 Introduction Electrodeposition of titanium (Ti) in chlorides [1–5], fluorides [6–10], and mixtures of them [11–17] has been investigated for electrowinning or eletrorefining of Ti. In these investigations, the electrolysis is usually carried out at 400–900 °C because the electrolytes of chlorides, fluorides, and the mixtures have high melting points. Compared to a high-temperature process, a low-temperature process has advantages, such as lower energy consumption for heating * Kazuhiro Kumamoto kumamoto.kazuhiro.43v@kyoto‑u.jp * Tetsuya Uda uda.tetsuya.5e@kyoto‑u.ac.jp 1
Department of Materials Science and Engineering, Graduate School of Engineering, Kyoto University, Yoshidahonmachi, Sakyo‑ku, Kyoto 606‑8501, Japan
and longer lifetime of the electrolytic cell. In addition, some polymers have heatproof temperatures lower than 400 °C. For example, the continuous operating temperature of polytetrafluoroethylene (PTFE) is 260 °C [18]. KaptonHN, which is a kind of polyimide, can be used up to 400 °C [19]. At a lower temperature, such polymers can facilitate the design of the cell. Therefore, many works focus on organic solvents [20–24] and ionic liquids [25–36] as electrolyte to produce Ti around room temperature. Mukhopadhyay et al. [26, 27] investigated the electrodeposition of Ti in 1-butyl3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIm]BTA) to which titanium tetrachloride was added. They observed the growth of Ti deposits on a gold substrate by using in situ scanning tunneling microscopy (STM) [27]. The maximum height of the deposits was 10–20 Å. O’Grady et al. [32] and Zhang et al. [33] claimed that titanium dioxide was partly reduced to metallic Ti by electrolysis in mixtures
13
Vol.:(0123456789)
of imidazolium-based ionic liquid and aluminum trichloride. However, as mentioned in other papers [24, 34–37], there is no evidence for the presence of bulk Ti metal such as X-ray diffraction (XRD) pattern
Data Loading...
