Reserch Of Aluminum Electrodeposition Using AlCl₃-Et₃NHCl Ionic Liquid Under High Gravity Field

Aluminum was successfully electrodeposited on stainless steel electrodes from aluminum chloride (AlCl3)/triethylamine hydrochloride (Et3NHCl) ionic liquids by constant current electrolysis under magnetic stirring conditions and super gravity conditions. Electrical viscosities and conductivities of different molar ratio of AlCl3/Et3NHCl ionic liquid were measured under different temperatures. In this paper, the influence of several experiment conditions on electrodeposition was investigated. The influence of high gravity on aluminum deposition in ionic liquid was researched.The results indicated that the electrical conductivities of ionic liquids decreased as molar ratio of AlCl3/Et3NHCl increased. The electrical conductivities of ionic liquids increased as the electrolyte temperature increased, following the Arrhenius behavior. When the molar ratio of AlCl3/Et3NHCl ionic liquid increased, the viscosities of ionic liquids increased. The viscosities of ionic liquids decreased as the electrolyte temperature increased, with a linear relationship of Ink and T-1.In the super gravity field, with the gravity coefficients increased, cell voltage decreased, but current efficiency and deposition rate increased. Cell voltage and deposition rate ascended with the enhancement of current density, but current efficiency reduced.Compared with earth gravity field, the current efficiency and deposition rate under super gravity field increased significantly. The results revealed that the current efficiency can be achieved about from 87% to 94% and the deposition rate at the range from 0.33 to 0.53μm-min-1. The current efficiency under earth gravity field can only reached 78% and the deposition rate of 0.35μm·min-1. Under the same current density, current efficiency under super gravity field was 1.4～1.7 times of that at earth gravity field. The morphology and chemical composition of aluminum deposits were characterized by scanning electron microscope coupled with EDS microanalysis. Dendrite aluminums were easily obtained in earth gravity field and the coatings were poor adherent. The electrodeposits obtained under super gravity field were uniform, dense and dendrite coatings were avoided under different gravity filed. Aluminum coatings showed good adherent. The purity of aluminum electrodeposits on stainless steel electrodes was about 97%(w).