Theses and Dissertations from UMD

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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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Subject: search.filters.subject.Copper

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Now showing 1 - 5 of 5
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    Characterization of Copper Covetic Bulk and Films: Copper with High Carbon Content
    (2016) Isaacs, Romaine Antonio; Salamanca-Riba, Lourdes G; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Incorporation of carbon nanostructures in metals is desirable to combine the strongly bonded electrons in the metal and the free electrons in carbon nanostructures that give rise to high ampacity and high conductivity, respectively. Carbon in copper has the potential to impact industries such as: building construction, power generation and transmission, and microelectronics. This thesis focuses on the structure and properties of bulk and thin films of a new material, Cu covetic, that contains carbon in concentrations up to 16 at.%. X-ray photoelectron spectroscopy (XPS) shows C 1s peak with both sp2 and sp3 bonded C measuring up to 3.5 wt.% (16 at.%). High resolution transmission electron microscopy and electron diffraction of bulk covetic samples show a modulated structure of ≈ 1.6 nm along several crystallographic directions in regions that have high C content suggesting that the carbon incorporates into the copper lattice forming a network. Electron energy loss spectra (EELS) from covetics reveal that the level of graphitization from the source material, activated carbon, is maintained in the covetic structure. Bulk Cu covetics have a slight increase in the lattice constant, as well as <111> texturing, or possibly a different structure, compared to pure Cu. Density functional theory calculations predict bonding between C and Cu at the edges and defects of graphene sheets. The electrical resistivity of bulk covetics first increases and then decreases with increasing C content. Cu covetic films were deposited using e-beam and pulsed laser deposition (PLD) at different temperatures. No copper oxide or any allotropes of carbon are present in the films. The e-beam films show enhanced electrical and optical properties when compared to pure Cu films of the same thickness even though no carbon was detected by XPS or EELS. They also have slightly higher ampacity than Cu metal films. EELS analysis of the C-K-edge in the PLD films indicate that graphitic carbon is transferred from the bulk into the films with uniform carbon distribution. PLD films exhibit flatter and higher transmittance curves and sheet resistance two orders of magnitude lower than e-beam films leading to a high figure of merit as transparent conductors.
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    COPPER CORROSION IN THE FLOWERS OF SULFER TEST ENVIRONMENT
    (2015) Mahadeo, Dinesh Michael; Pecht, Michael G; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Sulfur, present in the environment in the form of sulfur dioxide and hydrogen sulfide, can produce failure in electronics. In particular, copper, which is used extensively in electronic products, is subject to corrosion in the presence of sulfur. This thesis examines the corrosion of copper under the Flowers of Sulfur (FoS) test at varying temperatures and durations. The FoS test setup, described in ASTM B809, was initially designed to evaluate surface finish porosity, but this setup may have boarder application. To expand the applicability of the FoS test, it is important to characterize the test environment. To this end, a systematic study of copper corrosion was conducted through weight gain measurements of copper coupons that were subjected to FoS test environments. From the test results, a model was developed that correlates copper sulfide thickness to temperature and time under the FoS test. This model can be used to determine test conditions given a target field environment.
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    The Effect of CO2 on Copper Partitioning in Sulfur- Free and Sulfur-Bearing Felsic Melt-Vapor-Brine Assemblages
    (2012) Tattitch, Brian Christopher; Candela, Philip; Piccoli, Philip; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Analysis of fluid inclusions from porphyry copper deposits (PCD) reveals that magmatic vapor and/or brine are vital for the removal of copper from arc magmas and its transport to the site of ore formation. Experiments in melt-vapor-brine systems allow for investigating the partitioning of copper between silicate melts and volatile phases under magmatic conditions. The presence of CO2 affects both the pressure of vapor saturation and the composition of exsolving volatile phases. However, PCD are primarily sulfide ore deposits, and the role of sulfur must also be examined as part of magmatic-hydrothermal experiments. Therefore, the partitioning of copper in CO2 ± S-bearing experiments was examined in an attempt to provide insights into copper partitioning and the generation of PCD. I present the results from experiments performed at 800 °C and 100 MPa in CO2-bearing melt-vapor-brine systems with XCO2 = 0.10 and 0.38. The compositions of vapor and brine inclusions and run-product glasses were used to determine the compositions of the magmatic phases. The partitioning of copper between brine and vapor (DCu b/v ±2σ) increases from 25(±6) to 100 (±30) for sulfur-free experiments and increases from 11(±3) to 95(±23) for sulfur-bearing experiments as XCO2 is increased from 0.10 to 0.38. The partitioning of copper between vapor and melt (DCu v/m ±2σ) decreases from 9.6(±3.3) (sulfur-free, HCl-bearing), 18(±8) (sulfur-bearing, HCl-free), and 30(±11) (sulfur-bearing, HCl-bearing) at XCO2 = 0.10, to 2(±0.8)(HCl-free) at XCO2 = 0.38, sulfur-free or sulfur-bearing. These data demonstrate that copper partitioning in sulfur-free, CO2-bearing systems is controlled by the changes in the salinity of the vapor and brine corresponding to changes in XCO2. Sulfur-bearing experiments demonstrate that magmatic vapors are enriched in copper in the presence of sulfur at low XCO2. However, the enrichment of copper in the magmatic vapor is suppressed for sulfur-bearing systems at high XCO2. The MVPart model presented by Candela and Piccoli (1998) was modified to incorporate CO2 to predict trends in efficiency of removal of copper into exsolving CO2-bearing magmatic volatile phases. The CO2-MVPart model predicts two to three times lower efficiency for CO2-rich (XCO2 = 0.38) magmatic volatile phases compared to low-CO2 (XCO2 ≤ 0.10) systems.
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    FORENSIC INVESTIGATION TECHNIQUES FOR INSPECTING ELECTRICAL CONDUCTORS INVOLVED IN FIRES FOR ARC AND MELT BEADS
    (2012) Hussain, Nasir; Sunderland, Peter B; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The objective of this research was to determine, experimentally, if distinguishing characteristics exist between the beads formed on energized and non-energized wires exposed to various thermal insults. Most of research published in the literature has not tested energized and non-energized wires under the same thermal conditions. The tests in this study were conducted using convective, radiative and combined convective/radiative thermal exposures. Wires were tested in both energized and non-energized states. Energized wires were tested under "load" and "no load" conditions. Beads formed on both the energized and non-energized wires as results of thermal exposure. Beads were analyzed externally and internally with stereo microscope, SEM/EDS, and a metallurgical microscope. No clear trends or distinguishing visual or microscopic characteristics between the beads formed on energized and non-energized wires were found. The bead analysis methods used during this research showed that it is not possible to distinguish between the beads formed on energized and non-energized wires exposed to various thermal insults.
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    Methods of Making
    (2007-05-15) Lock, Benjamin Christopher; Ruppert, John; Art; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    I am drawn to tools, their applications, and the way things work. The action and process of manipulating and transforming material to create formal visual statements is vital to my sculpture. I utilize and respond to material and process, allowing for the work to develop through its creation. Relationships of form and space interest me. Not only do I find beauty in material, it also exists in the tension and the power of a space within or between forms. These interactions in my work help formulate the visual language through which the metaphor is present. I hope to capture and express a sensibility to which one can relate. This thesis will further discuss the manner in which I make sculpture. It will be a compliment to the artwork and an attempt to put to words the conceptual basis for the forms I create and the spaces they compose.