RESEARCH PAPER |
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Study on Cathodic Reduction Process During the Preparation of Al-Cu-Y Alloy by Molten Salt Electrolysis via Fluoride-Oxide System |
WANG Xu, LIAO Chunfa, JIAO Yunfen, TANG Hao
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School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 |
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Abstract Al-Cu-Y alloys were prepared in this work by molten salt electrolysis via fluoride-oxide system which was composed of electrolyte (Na3AlF6-AlF3-LiF-MgF2) and oxide (Al2O3-CuO-Y2O3). Cathodic reduction process of Al2O3, CuO and Y2O3 were analyzed by cyclic voltammetry. Components and phase composition of alloy samples, which had been prepared by aluminum thermal reduction and molten salt electrolysis, were characterized by scanning electron microscopy and energy dispersive spectroscopy. The results showed that the Al-Cu-Y alloys can be prepared in the AlF3-NaF-5wt%LiF-5wt%MgF2(n(NaF)/n(AlF3)=2.2) eutectic system with mixed oxide (Al2O3-CuO-Y2O3) through 2 hours, and the conditions of temperature, cell voltage and cathode current density are 1 208 K, 3.0 V and 0.7 A/cm2, respectively. Cu (Ⅱ) ions in carbonaceous electrode surface can be reduced to zero valence directly, and Y(Ⅲ) ions cannot be reduced to zero valence directly, but strengthening phase Al3Y can be formed through electrochemical reduction and alloyed process on the surface of preforming active Al-Cu cathode. Meanwhile, Al2Cu and Al3Y phase enriched at the grain boundaries of aluminum matrix. Al-Cu-Y alloys can also be prepared by aluminum thermal reduction from mixed Al-CuO-Y2O3, but content of Cu and Y were difficult to control owing to the enrichments of AlCu and AlY phases at the grain boundaries, and many impurities (O, C) also remained in the alloy.
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Published:
Online: 2018-05-08
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