Fundamental studies on electrochemical production of dendrite-free aluminum and titanium-aluminum alloys

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dc.contributor Gupta, Subhadra
dc.contributor Warren, Garry
dc.contributor Bao, Yuping
dc.contributor Dean, Derrick R.
dc.contributor.advisor Reddy, R. G. Pradhan, Debabrata 2017-03-01T14:37:44Z 2017-03-01T14:37:44Z 2010
dc.identifier.other u0015_0000001_0000502
dc.identifier.other Pradhan_alatus_0004D_10526
dc.description Electronic Thesis or Dissertation
dc.description.abstract A novel dendrite-free electrorefining of aluminum scrap was investigated by using AlCl_3 -1-Ethyl-3-methyl-imidazolium chloride (EMIC) ionic liquid electrolyte. Electrodeposition of aluminum were conducted on copper/aluminum cathodes at voltage of 1.5 V, temperatures (50-110ºC), stirring rate (0-120 rpm), molar ratio (MR) of AlCl_3 :EMIC (1.25-2.0) and electrode surface modification (modified/unmodified). The study was focused to investigate the effect of process variables on deposit morphology, cathode current density and their role in production of dendrite-free aluminum. The deposits were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Modified electrodes and stirring rate (60 rpm) eliminate dendritic deposition by reducing cathode overpotential below critical overpotential (-0.54 V) for dendrite formation. Pure aluminum (>99%) was deposited with current efficiency of 84-99%. Chronoamperometry study was conducted using AlCl_3 -EMIC and AlCl_3 -1-Butyl-3-methyl-imidazolium chloride (BMIC) (MR = 1.65:1) at 90ºC to understand the mechanism of aluminum electrodeposition and find out diffusion parameter of electroactive species Al_2 C_7 ^- . It was concluded that electrodeposition of aluminum is a diffusion controlled instantaneous nucleation process and diffusion coefficient of Al_3 C_7 ^- was found to be 5.2-6.9 × 10-11 m^2 /s and 2.2 × 10-11 m^2 /s for AlCl_3 -EMIC and AlCl_3 -BMIC, respectively. A novel production route of Ti-Al alloys was investigated using AlCl_3 -BMIC-TiCl_4 (MR = 2:1:0.019) and AlCl_3 -BMIC (MR = 2:1) electrolytes at constant voltages of 1.5-3.0 V and temperatures (70-125°C). Ti sheet was used as anode and cathode. Characterization of electrodeposited Ti-Al alloys was carried out using SEM, EDS, XRD and inductively coupled plasma-optical emission spectrometer (ICP-OES). Effect of voltage and temperature on cathode current density, current efficiency, composition and morphology of Ti-Al alloys were determined. The Ti-Al alloys containing about 13-27 atom % Ti were produced using both electrolytes. The current efficiency of AlCl_3 -BMIC was varies between 79-87%. But lower current efficiency (25-38%) was obtained for AlCl_3 -BMIC-TiCl_4 electrolytes due to the formation of TiCl_3 passive layer on the electrodes. To increase the productivity, constant current method (160-210 A/m^2 ) was implemented. This fundamental study on low temperature production of dendrite-free aluminum and Al-Ti alloys is not only efficient but also opens a novel route in aluminum and titanium process metallurgy.
dc.format.extent 189 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Engineering, Metallurgy
dc.subject.other Materials Science
dc.title Fundamental studies on electrochemical production of dendrite-free aluminum and titanium-aluminum alloys
dc.type thesis
dc.type text University of Alabama. Dept. of Metallurgical and Materials Engineering Metallurgical/Materials Engineering The University of Alabama doctoral Ph.D.

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