Browsing by Subject "copper"
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Item Binderless Jetting: Additive Manufacturing of Metal Parts via Jetting Nanoparticles(University of Texas at Austin, 2017) Bai, Yun; Williams, Christopher B.Binder Jetting AM has been used to fabricate metal parts by first jetting a binder into powder bed; the resulting green part is then thermally post-processed wherein the binder is removed and the metal particles are sintered. In this work, the authors replace conventionally-used polymeric binders with nanoparticle suspensions as a means for binding metal powder bed particles together. After being deposited into the powder particles’ interstices, the jetted nanoparticles are sintered at a low temperature via a heated powder bed to provide strength to the printed green part. Regions of the powder bed that do not receive the jetted nanoparticle suspension remain as loose powder as the sintering temperature of the nanoparticles is significantly lower than the larger powder bed particles. The concept of printing metal by jetting a nanoparticle binder made of the same material is demonstrated in the context of copper through printing copper parts with satisfactory green strength.Item Chemical Vapour Deposition of Amorphous Ru(P) Thin Films from Ru Trialkylphosphite Hydride Complexes(2012-09) McCarty, W. Jeffrey; Yang, Xiaoping; Anderson, Lauren J. D.; Jones, Richard A.; McCarty, W. Jeffrey; Yang, Xiaoping; Anderson, Lauren J. D.; Jones, Richard A.The ruthenium phosphite hydride complexes H2Ru(P(OR)(3))(4) (R = Me (1), Et (2), Pr-i (3)) were used as CVD precursors for the deposition of films of amorphous ruthenium-phosphorus alloys. The as-deposited films were X-ray amorphous and XPS analysis revealed that they were predominantly comprised of Ru and P in zero oxidation states. XPS analysis also showed the presence of small amounts of oxidized ruthenium and phosphorus. The composition of the films was found to depend on ligand chemistry as well as the deposition conditions. The use of H-2 as the carrier gas had the effect of increasing the relative concentrations of P and O for all films. Annealing films to 700 degrees C under vacuum produced films of polycrystalline hcp Ru while a flowing stream of H-2 resulted in polycrystalline hcp RuP.Item Copper source optimization for use in moderated positron apparatus(2008) Brand, Alexander; Manfred FinkWe attempted to develop an intense positron source by irradiating copper on an aluminum holder at the Nuclear Engineering Teaching Lab at the University of Texas at Austin. While this was not accomplished in the time frame required in order to include it in this thesis, I have included the design of the proposed sources for testing. Also included is my work on the development of the positron system while I was at NETL. Multiple sources are proposed to be developed with different thicknesses of copper to determine the optimum thickness and then develop a source around that known value.Item Degradation Of Trichloroethylene By Methanol-Grown Cultures Of Methylosinus Trichosporium Ob3B Pp358(1996-03) Fitch, Mark W.; Speitel, Gerald E.; Georgiou, George; Fitch, Mark W.; Speitel, Gerald E.; Georgiou, GeorgeA soluble methane monooxygenase-constitutive mutant strain of Methylosinus trichosporium OB3b, strain PP358, was grown with methanol as the carbon source, and the kinetics of trichloroethylene (TCE) degradation were determined. PP358 exhibited high TCE degradation rates under both oxygen- and carbon-limiting conditions. The optimal pseudo first-order rate constant for TCE was comparable to the values measured for cells grown,vith methane. We found that growth under oxygen-limiting conditions results in increased accumulation of polyhydroxybutyrate, which in turn correlates,vith higher transformation capacities for TCE. It was also shown that methanol inhibits TCE degradation only at high concentrations. Thus, methanol-grown cultures of PP358 represent an efficient system for the biodegradation of chlorinated hydrocarbons.Item Design and Characterization of Orthotropic Re-Entrant Auxetic Structures Made via EBM Using Ti6Al4V and Pure Copper(University of Texas at Austin, 2011-08-17) Yang, L.; Harrysson, O.; West, H. II; Cormier, D.An orthotropic 3D re-entrant honeycomb structure that exhibits a negative Poisson’s ratio was designed and fabricated via the electron beam melting (EBM) process. The modeling work established the relationships between various structural parameters and the mechanical properties of the auxetic structures. Compressive tests were performed on the re-entrant honeycomb samples made with Ti6Al4V as well as pure copper. Results of the strength, modulus and energy absorption for the two materials were compared with the theoretical models in order to verify the theoretical predictions.Item Designing Pulse Power Generators(IEEE, 2005-08) Davey, K.R.; Uglum, J.R.When the performance criteria for a pulsed power generator is power density, and the duty cycle remains short ( s), then copper coils with an exciter are favored over permanent magnet rotors. If the permanent magnets are replaced with copper coils, steel, and an exciter, with the same total weight, the copper coil alternative will return a higher magnetomotive force/weight, and thus a higher power density system. A variable metric optimization is completed for a generator, assuming the objective is to charge a capacitor bank. The equations governing allowed current density in capacitor charging applications and alternating current/direct current (ac/dc) resistance ratios are derived.Item Effect of Bimodal Powder Mixture on Powder Packing Density and Sintered Density in Binder Jetting of Metals(University of Texas at Austin, 2015) Bai, Yun; Wagner, Grady; Williams, Christopher B.The Binder Jetting Additive Manufacturing process provides an economical and scalable means of fabricating complex metal parts from a wide variety of materials. However, the performance metrics of the resulting sintered parts (e.g., thermal, electrical, and mechanical properties) are typically lower than traditionally manufactured counterparts due to challenges in achieving full theoretical density. This can be attributed to an imposed constraint on particle size and its deleterious effects on powder bed packing density and green part density. To address this issue, the authors explore the use of bimodal powder mixtures to improve the sintered density and material properties within the context of copper parts fabricated by Binder Jetting. The effectiveness of using bimodal powder mixtures in an effort to improve sintered density is studied in terms of particle size distribution and powder packing density.Item Electroforming Process to Additively Manufactured Microscale Structures(University of Texas at Austin, 2019) Patel, Krish; McNamee, Amelia; Silwal, BishalElectroforming is a metal forming process that forms parts through electrodeposition. The overall study and production of the copper mandrel were conducted by examining the growth and depth of the depositions at macroscopic levels. The study of the plating constant for a copper plate in copper sulfate was performed via the production of copper mandrels. Each mandrel was produced by performing multiple experiments and qualitatively and quantitatively examining the resultant depositions and the initial and final states of the experiment. The results were measured based on variations of current and voltage duration in the bath cycle, time duration, solution concentration, and change in mass of both the anode and cathode. The variables such as plating constant and direct current distribution are determined. It seems the rate at which the structure can be fabricated depends on the type of electrolytes used and the parts that are deposited can be scalable.Item An Exploration of Binder Jetting of Copper(University of Texas at Austin, 2014) Bai, Yun; Williams, Christopher B.The ability to fabricate geometrically complex copper shapes via Additive Manufacturing (AM) could have a significant impact on the design and performance of thermal management systems and structural electronics. In this research a Binder Jetting AM process (ExOne R2) was used to fabricate green parts made of high purity copper powder. Once printed, the green part was sintered under a reducing atmosphere to create copper parts in pure metal form. The authors varied (i) powder size, (ii) sintering profiles, and (iii) atmospheric control to explore their effects on final part density and shrinkage. The sintered part density was 85% of the theoretical value due to the relatively coarse powder and loose packing of the powder bed. The result demonstrates the feasibility of using Binder Jetting to create copper parts with complex geometries.Item Joining of Copper and Stainless Steel 304L Using Direct Metal Deposition(University of Texas at Austin, 2019) Zhang, Xinchang; Chen, Yitao; Pan, Tan; Cui, Wenyuan; Li, Lan; Liou, FrankIn the current study, the feasibility of joining pure copper (Cu) and stainless steel 304L (SS304L) through direct metal deposition process was investigated by material characterization. Samples were analyzed in terms of microstructure, elemental distribution, and tensile testing. Direct depositing pure copper on SS304L shows copper was mechanically rather than metallurgical bonded with SS304L due to the poor dissolubility of iron in copper. Iron was diffused into copper with a diluted distance of 1.5 mm and above that, pure copper deposits were obtained. Columnar structure was observed at the copper region near the interface while the columnar grains became finer away from the interface and finally, equiaxed structure was observed. Tensile testing shows the yield strength and ultimate tensile strength of combined materials (copper and SS304L) are 123 MPa and 250 MPa and samples fractured at the copper section with a ductile fracture mechanism. The bi-material interface survived the tensile test. The yield strength and ultimate tensile strength of as-fabricated pure copper are 95.02 MPa and 186.66 MPa, respectively.Item Laser-Induced Spall Of Aluminum And Aluminum Alloys At High Strain Rates(2007-12) Dalton, D. A.; Brewer, J.; Bernstein, A. C.; Grigsby, W.; Milathianaki, D.; Jackson, E.; Adams, R.; Rambo, P.; Schwarz, J.; Edens, A.; Geissel, M.; Smith, I.; Taleff, E.; Ditmire, T.; Dalton, D. A.; Brewer, J.; Bernstein, A. C.; Grigsby, W.; Milathianaki, D.; Jackson, E.; Taleff, E.; Ditmire, T.We conducted laser-induced spall experiments aimed at studying how a material's microstructure affects the tensile fracture characteristics at high strain rates (> 10(6) s(-1)). We used the Z-Beamlet Laser at Sandia National Laboratory to drive shocks and to measure the spall strength of aluminum targets with various microstructures. The targets were recrystallized, high-purity aluminum (Al-HP RX), recrystallized aluminum + 3 wt.% magnesium (Al-3Mg RX), and cold-worked aluminum + 3 wt.% magnesium (Al-3Mg CW). The Al-3Mg RX and Al-3Mg CW are used to explore the roles that solid-solution alloying and cold-work strengthening play in the spall process. Using a line-VISAR (Velocity Interferometer System for Any Reflector) and analysis of recovered samples, we were able to measure spall strength and determine failure morphology in these targets. We find that the spall strength is highest for Al-HP RX. Analysis reveals that material grain size plays a vital role in the fracture morphology and spall strength results.Item The Production and Perception of Bronze in Mycenaean Greece(2020-05-20) Winkley, Cassandra; Palaima, Thomas G.The Aegean Bronze Age, the period in Greek prehistory between 3000 BCE and 1100 BCE, is best characterized by the introduction and utilization of bronze metal. In particular, the alloy tin-bronze is associated with the later part of this period, and especially with the mainland culture of the Mycenaeans. The matter of tin-bronze production in Mycenaean Greece is problematic, primarily due to the fact that there is a lack of evidence that such an industry was even practiced by the Mycenaeans at the time. Thus, it is the goal of this paper to evaluate the evidence for metal trade and metallurgy provided by the archaeological record and in the corpus of Linear B tablets to determine the likelihood that the Mycenaeans actively produced tin-bronze. In doing so, certain aspects of Mycenaean society are revealed or further elaborated, namely the state of the mainland during the socio-economic collapse of the Mediterranean at the end of the Bronze Age.Item Selective Laser of a Copper-PMMA System(1991) Badrinarayan, B.; Barlow, J.W.The Selective Laser Sintering process was used to manufacture green copper parts from a copper-polymer mixture. PMMA was used as the polymer binder for the metal. The green part was fired in a furnace under reducing conditions to obtain a pure metal part. The metal-polymer system and the conditions used to make parts are described in this paper. The effect of laser parameters and particle sizes on part density are also discussed. Keywords: laser sintering, copper, polymer, part density, dwell time, shrinkage.Item TOWARDS THE LIMITS IN COPPER LATTICE PRODUCTION VIA FIBER LASER POWDER BED FUSION(University of Texas at Austin, 2023) Smet, M.; Li, G.; Goossens, L.R.; Buls, S.; Van Hooreweder, B.Additive manufacturing of copper, by means of Laser Powder Bed Fusion (LPBF), paves the way for innovation in thermal systems and heat transfer devices. Recent simulations have shown that by interchanging typical fin designs with more complex structures, an overall improvement in pressure drop and weight can be obtained while offering the same thermal performance. Here, small-scale lattice structures are especially of interest for AM as they form a reliable, periodic infill. However, until now, their study has been mainly theoretical. To analyze these structures in more detail, an in-house built LPBF machine at KU Leuven has been successfully used to manufacture pure copper parts. Measurements showed a conductivity exceeding 100%IACS, which is the result of low contamination and low porosity in the as-built material. In this work, the parameter optimization for thin-walled lattices is discussed, the limitations in terms of minimal feature size are described and physical mechanisms behind these limitations are uncovered.Item μ-SLS of Metals: Physical and Thermal Characterization of Cu- Nanopowders(University of Texas at Austin, 2015) Roy, N.K.; Yuksel, A.; Cullinan, M.A.Micro-scale selective laser sintering(μ-SLS) requires the use of nanoparticles(NPs) since the particle size needs to be an order of magnitude smaller than the melt pool in order to accurately sinter particles together to form a part. Most NPs properties are dependent upon size and thus, an exhaustive study of the physical and thermal properties of these NPs is required in order to successfully model and simulate the sintering process. In this paper we will present particle size characterization using Scanning electron microscopy (SEM), density measurements using He pycnometry, and X-ray Energy Dispersive Spectroscopy that were carried out to characterize the copper(Cu) nanopowder samples. Furthermore, the samples were sintered with different powers to estimate optimum power and exposure times and the results have been discussed along with further scope of work for fully characterizing the particles.