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Title:Investigation of mechanical properties of copper and aluminum covetics using nanoindentation
Author(s):Braroo, Sakshi
Advisor(s):Jasiuk, Iwona M.; Mondal, Paramita
Department / Program:Civil & Environmental Eng
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:Covetics are novel metal-carbon materials invented by Third Millennium Metals, LLC (TMM). Covetics involve copper, aluminum, tin, zinc, silver, gold and other metals or their alloys which are infused with a high weight percent of carbon powder (up to 10 %). The amount of carbon in covetics far exceeds the solubility limits of these metals and carbon. The covetics are made using a proprietary method of carbon catalyzation which uses molten metal or metal alloys as an ionizing medium. In this thesis we study local mechanical properties of copper and aluminum alloy based covetics using the nanoindentation technique. Covetic copper 10200 and aluminum 6061 alloy samples along with standard, commercially available copper 10200, obtained from TMM, were tested. All the samples were as-cast and not heat treated. The copper covetic samples had carbon contents of 0, 3, 5 and 9 weight percent whereas the aluminum covetic samples had carbon contents of 0 and 2.3 weight percent as reported by TMM. Elastic modulus, hardness and friction coefficients were measured. In addition, viscoelastic properties such as storage and complex moduli were assessed for all the covetic samples and standard sample. The obtained values were compared with each other and with those available in literature. The value of elastic modulus for standard copper 10200 was found to be lower by 7 % from the literature reported value. The copper covetic samples studied here were found to have lower elastic modulus and hardness values by 13.5 % - 16.8 % and 4.8 % - 10.8 %, respectively when compared to those measured for a standard copper 10200 sample. The results did not show a clear trend with an increase in carbon content. The aluminum covetic samples also exhibited lower elastic modulus than the modulus of aluminum 6061 reported in literature. However, the aluminum covetic samples exhibited a clear increase in modulus and hardness with an increase in carbon content. In addition, 200 nm thick thin-film samples made of pure copper and copper covetic (carbon content 5 wt.%) were procured from University of Maryland. Several nanoindentation tests were performed at multiple times on these samples to measure their elastic modulus and hardness. Different mean hardness and elastic modulus values were obtained at different times possibly due to spatial heterogeneity in material properties and possible changes in the thin-films over time. The elastic modulus and hardness values measured in this study for covetic thin film were, in general, lower than those for the pure copper thin film of the same thickness. All results reported in this study are based on results obtained from one sample of each material type and testing only few locations on each sample. More comprehensive analysis should be done in the future.
Issue Date:2014-01-16
Rights Information:Copyright 2013 Sakshi Braroo
Date Available in IDEALS:2014-01-16
Date Deposited:2013-12

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