Qibo Zhang

Synthesis of micro-FeTi powders by direct electrochemical reduction of ilmenite in CaCl2-NaCl molten salt

Micro-ferrotitanium powders have been prepared by molten salt electrolysis via directly electrochemical reduction of solid ilmenite in eutectic CaCl2-NaCl melt at 973 K. In the direct electrochemical reduction process, the reduction of FeTiO3 first gives rise to the formation of Fe and CaTiO3, which as intermediates will be further deoxidized at the interface of iron metals, solid CaTiO3 matrix, and electrolyte to directly form ferrotitanium alloy powders in porous structure. Furthering the electrolytic time can promote the dense structure of ilmenite pellet turn to be more porous, indicating pores inside the pellet are sufficient for the diffusion of oxygen ions. Based on the reduction behavior of partially reduced powders in metallic cavity electrode during the cathodic potentiostatic electrolysis, it shows that the slow deoxidization rate is mainly caused by the more and more difficult reduction of CaTiO3 than that of FeTiO3.

Electrodeposition of Al-Ti alloy on mild steel from AlCl3-BMIC ionic liquid

The electrodeposition of Al-Ti alloy on a mild steel substrate is examined in a Lewis acidic 66.7–33.3xa0mol% AlCl3-1-buthyl-3-methylimidazolium chloride ionic liquid containing TiCl4. Dense and compact Al-Ti alloy coatings with Ti content ranging from 5.3 to 11.4xa0at.% can be obtained under optimized conditions. The applied current densities and TiCl4 concentration are found to play central roles in controlling the alloy compositions and surface morphologies of the resultant Al-Ti alloy coatings. Ti content in Al-Ti alloys increases with initial increase in the current density and decreases when the current density is beyond 5xa0mAxa0cm−2. In addition, the enhanced corrosion resistance of the mild steel substrate by the deposited Al-Ti alloy layers is evaluated via electrochemical techniques. The Al-Ti alloy coatings show much higher corrosion resistance than single Al coating, and this performance is improved with the increase of the Ti content.

The Effect of Water on the Tin Electrodeposition from [Bmim]HSO4 Ionic Liquid

The electrodeposition of tin from SnO in ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) in the presence of water at different cathodic potential was investigated. With the addition of water to [Bmim]HSO4 ionic liquid, the electrochemical window of the electrolyte decreases and the reduction potential of Sn(II) positively shifts. The water content of ionic liquid electrolyte has a distinct effect on morphology of the deposits. As water content increased from 0 to 50% (v/v), the morphology of deposits varies from granular to hexagonal rod-like, then to hollow tubular, and finally to wire-like. The XRD phase analysis showed that both Sn and CuSn alloys were deposited in ionic liquid/water mixtures. However, in dried ionic liquids only Cu3Sn was obtained, surprisingly. The difference in the structure might be attributed to the various interactions of the ions with the Cu substrate. In addition, the deposition potential was found to play a significant role in the morphology of deposits.

Electrodeposition of Ni-Mg alloys from 1-butyl-3-methylimidazolium chloride/glycerin eutectic-based ionic liquid

The electrodeposition of Ni-Mg alloys in 1-butyl-3-methylimidazolium chloride/glycerin (BMIC/GL, 1:1xa0M ratio) eutectic-based ionic liquid containing 0.1xa0M MgCl2 and 0.05xa0M NiCl2 was investigated. It is found by cyclic voltammograms and analysis of the chronoamperometric transient that Mg can be co-deposited with Ni under the inducement effect of Ni in this solvent, and the co-electrodeposition of Ni and Mg on a glassy carbon electrode is a diffusion-controlled process, which follows an instantaneous nucleation and three-dimensional growth pattern. In addition, the composition, surface morphology, structure, and property for hydrogen storage of Ni-Mg alloy deposits were characterized by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopic (SEM), and charge and discharge test, respectively. The deposition potential plays a central role in controlling the composition, surface morphology as well as the electrochemical hydrogen storage capacity of the resultant Ni-Mg alloys. The alloy obtained at −1.2xa0V (vs. Ag) is a two-phase mixture consisting of a solid solution and an amorphous phase, which exhibits the best electrochemical capacity of 81.6xa0mAhxa0g−1.