2013 Fiscal Year Annual Research Report
電解採取法及び電解還元法によるチタン新製造法の開発研究
| Project/Area Number |
12F02742
|
|---|
| Research Institution | Waseda University |
|---|
Principal Investigator |
不破 章雄 早稲田大学, 理工学術院, 教授
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
GRANATA Giuseppe 早稲田大学, 理工学術院, 外国人特別研究員
|
|---|
| Keywords | Titanium / sub-chloride / Electro-winning / new process / molten salt electrolysis / Electro-deposition |
|---|
| Research Abstract |
Titanium tetrachloride (TiCl_4) was fed as gas (423 K) into a molten salt NaCl-KC1 1:1 at 973 K where it was successfully converted into titanium dichloride (TiCl_2) by a spontaneous disproportion reaction with a titanium plate (Ti) also immersed in molten salt. Concentration of the as produced TiCl_2 was around 30% of total titanium detected in the molten salt but this value seems to be affected by the quality of titanium plate since oxidized portions might reduce the active titanium surface. Other results suggest that TiCl_4 gets first dissolved in the molten salt and then it reacts with titanium. Furthermore, no significant contribution of the direct gas solid-reaction was observed. Cyclic voltammetry and linear scan voltammetry also revealed the presence of Ti^<2+> in the system and the possibility of reducing it by applying a potential more negative than -1.1 V. Therefore a constant working potential of -1.4 V (vs Ag/AgCl) was provided to the same titanium plate where the disproportion reaction takes place and the in-situ produced TiCl_2 was successfully electrodeposited on it. SEM/EDS micrograph of titanium cathode after electro deposition showed that the deposited titanium had mainly a grain like morphology with a minor presence of needle like crystals. Currently an improvement of the disproportion reaction by using an oxide-free titanium plate and a deeper electrochemical study are under investigation.
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The experimental campaign proceeds as planned but with a small delay due to ordinary experimental problems. The major issue is currently related to the presence of oxidized portions of titanium on the plate where disproportion and electro deposition take place.
|
| Strategy for Future Research Activity |
Current experiments are being performed in order to solve the issue related to the oxidized portion of titanium on the plate/cathode. In particular, taking as output variable the production yield of TiCl_2, the addition of magnesium to reduce and precipitate TiO_2 has been put under investigation. Whereas results will not be as expected, the application of a reverse potential transient to the titanium cathode will be also investigated with the aim to produce chlorine gas which then converts the oxidized portions of titanium (Tio_2) to titanium tetrachloride (TiCl_4).
Furthermore, next experiment will consist of an electrochemical study to deepen the involved mechanisms and to improve the electro winning operation. In particular, by performing cyclic voltammetry, chronopotentiometry and chronoamperometry, few important parameters such as the diffusion coefficient and the amount of electrons involved in each electrochemical reaction will be evaluated along with the nucleation mechanism.
|
