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Coexistence Pressure For A Martensitic Transformation From Theory And Experiment: Revisiting The Bcc-Hcp Transition Of Iron Under Pressure, Nikolai A. Zarkevich, Duane D. Johnson 2015 Ames Laboratory

Coexistence Pressure For A Martensitic Transformation From Theory And Experiment: Revisiting The Bcc-Hcp Transition Of Iron Under Pressure, Nikolai A. Zarkevich, Duane D. Johnson

Ames Laboratory Publications

The coexistence pressure of two phases is a well-defined point at fixed temperature. In experiment, however, due to nonhydrostatic stresses and a stress-dependent potential energy barrier, different measurements yield different ranges of pressure with a hysteresis. Accounting for these effects, we propose an inequality for comparison of the theoretical value to a plurality of measured intervals. We revisit decades of pressure experiments on the bcc↔hcp transformations in iron, which are sensitive to nonhydrostatic conditions and sample size. From electronic-structure calculations, we find a bcc↔hcp coexistence pressure of 8.4GPa. We construct the equation of state for competing phases ...


Material Coefficient Of Thermal Expansion Investigation For Use In Additive Manufacturing Fused Deposition Modeling For Composite Tooling, Daniel Miller 2015 The University of Southern Mississippi

Material Coefficient Of Thermal Expansion Investigation For Use In Additive Manufacturing Fused Deposition Modeling For Composite Tooling, Daniel Miller

Master's Theses

Polymer matrix composites are being used to manufacture light weight, high stiffness aircraft structures. These structures are often manufactured from carbon fiber reinforced epoxy. When these structures are damaged, they must be repaired to restore strength to the component to avoid the cost and logistics of having replacements parts. Occasionally, these repairs require tooling in order to make a quality repair, however, tooling generally has a long lead time. Additive manufacturing could be used to manufacture rapid tooling to create tooling for composite repairs. The issue is that polymer printed tooling has a much higher coefficient of thermal expansion (CTE ...


Cure Kinetics, Morphologies, And Mechanical Properties Of Thermoplastic/Mwcnt Modified Multifunctional Glassy Epoxies Prepared Via Continuous Reaction Methods, XIAOLE CHENG 2015 University of Southern Mississippi

Cure Kinetics, Morphologies, And Mechanical Properties Of Thermoplastic/Mwcnt Modified Multifunctional Glassy Epoxies Prepared Via Continuous Reaction Methods, Xiaole Cheng

Dissertations

The primary goal of this dissertation is to develop a novel continuous reactor method to prepare partially cured epoxy prepolymers for aerospace prepreg applications with the aim of replacing traditional batch reactors. Compared to batch reactors, the continuous reactor is capable of solubilizing and dispersing a broad range of additives including thermoplastic tougheners, stabilizers, nanoparticles and curatives and advancing epoxy molecular weights and viscosities while reducing energy consumption.

In order to prove this concept, polyethersulfone (PES) modified 4, 4’-diaminodiphenylsulfone (44DDS)/tetraglycidyl-4, 4’-diaminodiphenylmethane (TGDDM) epoxy prepolymers were firstly prepared using both continuous reactor and batch reactor methods. Kinetic studies ...


Generalized Ellipsometry Analysis Of Anisotropic Nanoporous Media: Polymer-Infiltrated Nanocolumnar And Inverse-Column Polymeric Films, Dan Liang 2015 University of Nebraska–Lincoln

Generalized Ellipsometry Analysis Of Anisotropic Nanoporous Media: Polymer-Infiltrated Nanocolumnar And Inverse-Column Polymeric Films, Dan Liang

Electrical Engineering Theses and Dissertations

Characterization of the structural and optical properties is a subject of significance for nanoporous material research. However, it remains a challenge to find non-destructive methods for investigating the anisotropy of porous thin films with three-dimensional nanostructures. In this thesis, a generalized ellipsometry (GE) analysis approach is employed to study two types of anisotropic nanoporous media: slanted columnar thin films (SCTFs) with polymer infiltration and inverse-SCTF polymeric films. The thesis presents the physical properties obtained from GE analysis, including porosity, columnar shape, principal optical constants, birefringence, etc.

The thesis reports on using a GE analysis approach, combining the homogeneous biaxial layer ...


Characterizing Water As Gap Fill For Double Glazing Units, Bright Adu 2015 Western Kentucky University

Characterizing Water As Gap Fill For Double Glazing Units, Bright Adu

Masters Theses & Specialist Projects

The use of sunlight has always been a major goal in the design and operation of commercial buildings to minimize electrical consumption of artificial lighting systems. Glazing systems designed to allow optimal visible light transmission also allow significant unwanted direct solar heat gain caused by infrared light. Conversely, glazing systems that are designed to reflect unwanted direct solar heat gain significantly reduce the transmittance of visible light through windows. The goal of this research was to characterize the performance of water as gap-fill for double-glazing units in eliminating the compromises that exist in current glazing systems with respect to light ...


Ultrahigh Density Sub-10 Nm Cobalt Nanowire Arrays: Simulation, Fabrication, And Characterization, Yuan Tian 2015 University of Nebraska - Lincoln

Ultrahigh Density Sub-10 Nm Cobalt Nanowire Arrays: Simulation, Fabrication, And Characterization, Yuan Tian

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

The simulation, fabrication, and characterization of self-assembled ultrahigh density sub-10nm Co nanowire arrays are presented in this dissertation. The general phase separation nanowire growth simulation was operated based on a modified Ising model. The fabrication process can be summarized as the binary Co-X systems lateral phase separation during physical vapor deposition – the plasma layer deposition with a single alloy Co-X target. The “X” stands for Al or Si. The nanowire fabrication and diameter deduction was achieved by balancing the growth rate and surface diffusivity. For Co-Al binary system, the formed sub-10 nm Co nanowires are of face-centered cubic structure through ...


Mitigation Of Aging In Low Voltage Power Cables In Nuclear Power Plants, Robert Jonathan York, Joseph Benjamin Ulrich, Grant Murphy, Daniel George Prather 2015 University of Tennessee - Knoxville

Mitigation Of Aging In Low Voltage Power Cables In Nuclear Power Plants, Robert Jonathan York, Joseph Benjamin Ulrich, Grant Murphy, Daniel George Prather

University of Tennessee Honors Thesis Projects

No abstract provided.


Reaction Kinetics Of Rare Earth And Actinide Materials, Brian Jon Jaques 2015 Boise State University

Reaction Kinetics Of Rare Earth And Actinide Materials, Brian Jon Jaques

Boise State University Theses and Dissertations

This dissertation presents the effects of atmosphere, time, and energy input (thermal and mechanical) on the kinetics of gas-solid and solid-solid reactions in systems of dysprosium, uranium, oxygen, and nitrogen. Accordingly, Chapter Two presents a novel synthesis technique used to form DyN via a gas-solid reaction between dysprosium and nitrogen. DyN was rapidly formed through a mechanochemical process in a high energy ball mill at ambient temperatures. The progress of the reaction was quantified using in situ temperature and pressure measurements coupled with microscopy and x-ray diffraction. It was found that the rate of the nitridation reaction is controlled by ...


Microstructure And Phase Analysis In Mn-Al And Zr-Co Permanent Magnets, Michael J. Lucis 2015 University of Nebraska-Lincoln

Microstructure And Phase Analysis In Mn-Al And Zr-Co Permanent Magnets, Michael J. Lucis

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

In America’s search for energy independence, the development of rare-earth free permanent magnets is one hurdle that still stands in the way. Permanent magnet motors provide a higher efficiency than induction motors in applications such as hybrid vehicles and wind turbines. This thesis investigates the ability of two materials, Mn-Al and Zr-Co, to fill this need for a permanent magnet material whose components are readily available within the U.S. and whose supply chain is more stable than that of the rare-earth materials. This thesis focuses on the creation and optimization of these two materials to later be used ...


Electrospinning Of Polycaprolactone Core-Shell Nanofibers With Anti-Cancer Drug, Sakib Iqbal, Mujibur Khan, Saheem Absar, Andrew Diamanduros, Samuel Chambers 2015 Georgia Southern University

Electrospinning Of Polycaprolactone Core-Shell Nanofibers With Anti-Cancer Drug, Sakib Iqbal, Mujibur Khan, Saheem Absar, Andrew Diamanduros, Samuel Chambers

Georgia Southern University Research Symposium

Encapsulation of a model anti-cancer drug, 5-Fluorouracul (5-FU) into biocompatible core-shell nanofibers of polycaprolactone (PCL) nanofibers was fabricated using a coaxial electrospinning process. Our work aims to solve these issues using a novel method of fabrication of fibers featuring confinement of drugs within a biodegradable core-shell structure, thereby permitting sustained release of drugs to specific sites of treatment, such as tissues affected with tumor cells. The coaxial electrospinning was performed using a sheath polymer solution consisting of a 14 wt% PCL solution and a 5 wt% solution of 5-FU as the core solution. Dimethylformamide (DMF) was used as the solvent ...


Crystal Nucleation Of Palladium-Doped Lithium Disilicate Glass, Gregory Humble 2015 Southern Polytechnic State University

Crystal Nucleation Of Palladium-Doped Lithium Disilicate Glass, Gregory Humble

Symposium of Student Scholars

The effect of concentration of palladium particles on crystal nucleation was investigated for lithium disilicate glass. The heterogeneous nucleation rate for 470°C and 480°C were calculated for a concentration of 0.001% palladium by weight. The DTA method of measuring nucleation and crystallization was used in this calculation.


Resurrecting “Poor Man’S Purple”: A Transdisciplinary Study Of Color-Shifted Pigments Used In An Encaustic Fayum Mummy Portrait Of Ancient Egypt, Brittany Archuleta, Alaggio B. Laurino, Cameron E. Quade, John-Paul D. Stroud, Jared L. Talley, Brittany L. Cannon, Ron Garnys, Darryl P. Butt, Glenn Gates, Janice Neri 2015 College of Social Sciences and Public Affairs, Boise State University

Resurrecting “Poor Man’S Purple”: A Transdisciplinary Study Of Color-Shifted Pigments Used In An Encaustic Fayum Mummy Portrait Of Ancient Egypt, Brittany Archuleta, Alaggio B. Laurino, Cameron E. Quade, John-Paul D. Stroud, Jared L. Talley, Brittany L. Cannon, Ron Garnys, Darryl P. Butt, Glenn Gates, Janice Neri

College of Engineering Presentations

During the Coptic period in Fayum Egypt, encaustic (i.e. wax) mummy portraits were painted onto wooden panels or linen and attached to the mummy trappings of the deceased. One such portrait, “32.6: The Bearded Man” (c. 170-180 AD), features an unidentified Roman-Egyptian displaying a purple clavi. The trace swath of purple in the portrait provides evidence as to the origins of the painting and the identity of the man. Nanoscale analysis of the pigment suggests a red organic material was color shifted using a metal salt to produce a “poor man’s purple” as opposed to the expensive ...


Towards Molecular Modification Of Carbon Nanotube Junctions In Thin Film Transistors, Noelia Caloca, A. Nicole Chang, Kari McLaughlin, David Estrada 2015 College of Arts and Sciences, Boise State University

Towards Molecular Modification Of Carbon Nanotube Junctions In Thin Film Transistors, Noelia Caloca, A. Nicole Chang, Kari Mclaughlin, David Estrada

College of Engineering Presentations

Carbon nanotube thin film transistors have recently been used on flexible and transparent substrates for applications in integrated circuits and display drivers. Such networks are of interest due to their relatively high carrier mobility and mechanical flexibility. However, the ION/IOFF ratio of these networks varies inversely with the carrier mobility, and advances in reducing the electrical and thermal resistance of nanotube junctions are needed to improve the device performance and reliability. The objective of this work is create a process to improve CNT TFT device performance by using 0-dimensional molecules to modify the physical properties of the ...


In-Vivo Corrosion And Fretting Of Modular Ti-6al-4v/Co-Cr-Mo Hip Prostheses: The Influence Of Microstructure And Design Parameters, Jose Luis Gonzalez Jr 2015 Florida International University

In-Vivo Corrosion And Fretting Of Modular Ti-6al-4v/Co-Cr-Mo Hip Prostheses: The Influence Of Microstructure And Design Parameters, Jose Luis Gonzalez Jr

FIU Electronic Theses and Dissertations

The purpose of this study was to evaluate the incidence of corrosion and fretting in 48 retrieved titanium-6aluminum-4vanadium and/or cobalt-chromium-molybdenum modular total hip prosthesis with respect to alloy material microstructure and design parameters. The results revealed vastly different performance results for the wide array of microstructures examined. Severe corrosion/fretting was seen in 100% of as-cast, 24% of low carbon wrought, 9% of high carbon wrought and 5% of solution heat treated cobalt-chrome. Severe corrosion/fretting was observed in 60% of Ti-6Al-4V components. Design features which allow for fluid entry and stagnation, amplification of contact pressure and/or increased ...


Towards The Perfect Optical Fiber, John Ballato 2015 Clemson University

Towards The Perfect Optical Fiber, John Ballato

Journal of the South Carolina Academy of Science

Optical fibers are being used in an ever more diverse array of applications today. Many of these modern applications are in high-power and, particularly, high power-per-unit-bandwidth systems where optical nonlinearities historically have not limited overall performance. Today, however, nominally weak effects, such as stimulated Brillouin scattering (SBS), are restricting continued scaling to higher optical powers. To address these limitations, the optical fiber industry has focused on fiber geometry-related solutions such as large mode area (LMA) designs. However, since all linear and nonlinear optical phenomena are fundamentally materials-based in origin, this paper identifies material solutions to present and future performance limitations ...


Oxide Dispersion Strengthened Nickel Based Alloys Via Spark Plasma Sintering, Somayeh Pasebani, Aniket K. Dutt, Jatuporn Burns, Indrajit Charit, Rajiv S. Mishra 2015 University of Idaho

Oxide Dispersion Strengthened Nickel Based Alloys Via Spark Plasma Sintering, Somayeh Pasebani, Aniket K. Dutt, Jatuporn Burns, Indrajit Charit, Rajiv S. Mishra

Materials Science and Engineering Faculty Publications and Presentations

Oxide dispersion strengthened (ODS) nickel based alloys were developed via mechanical milling and spark plasma sintering (SPS) of Ni–20Cr powder with additional dispersion of 1.2 wt% Y2O3 powder. Furthermore, 5 wt% Al2O3 was added to Ni–20Cr–1.2Y2O3 to provide composite strengthening in the ODS alloy. The effects of milling times, sintering temperature, and sintering dwell time were investigated on both mechanical properties and microstructural evolution. A high number of annealing twins was observed in the sintered microstructure for all the milling times. However, longer milling time contributed ...


Direct Observation Of The Recovery Of An Antiferroelectric Phase During Polarization Reversal Of An Induced Ferroelectric Phase, Hanzheng Guo, Xiaoli Tan 2015 Iowa State University

Direct Observation Of The Recovery Of An Antiferroelectric Phase During Polarization Reversal Of An Induced Ferroelectric Phase, Hanzheng Guo, Xiaoli Tan

Materials Science and Engineering Publications and Papers

Electric fields are generally known to favor the ferroelectric polar state over the antiferroelectric nonpolar state for their Coulomb interactions with dipoles in the crystal. In this paper, we directly image an electric-fieldassisted ferroelectric-to-antiferroelectric phase transition during polarization reversal of the ferroelectric phase in polycrystalline Pb0.99{Nb0.02[(Zr0.57Sn0.43)0.92Ti0.08]0.98}O3.With the electric-field in situ transmission electron microscopy technique, such an unlikely phenomenon is verified to occur by both domain morphology change and electron-diffraction analysis. The slower kinetics of the phase transition, compared with ferroelectric polarization reversal, is suggested to contribute to ...


Characterization Of High-Pressure-Die-Cast Magnesium Alloy Am60, Hooman Baghaei Anaraki 2015 The University of Western Ontario

Characterization Of High-Pressure-Die-Cast Magnesium Alloy Am60, Hooman Baghaei Anaraki

University of Western Ontario - Electronic Thesis and Dissertation Repository

The primary goal of this study is the characterization of high pressure die cast magnesium alloys AM60 so that the failure model which is proposed by J.Weiler can be validated for two new castings. The input variables of failure model can be determined by characterization of different regions within the castings. Based on the location of gate system, the desired regions are identified across both castings and tensile specimens are extracted from various regions. Therefore the local mechanical properties are determined, and fracture strain of samples ranges from 1.2 to 9.5%. The area fraction of porosities and ...


Söyleşi- Rauf H Eric, Güney Afrika'da Madencilik Ve Metal Kazanımı (Interview With Rauf H Eric, Mining And Metal Extraction In South Africa), Ahmet Deniz Bas 2015 Laval University

Söyleşi- Rauf H Eric, Güney Afrika'da Madencilik Ve Metal Kazanımı (Interview With Rauf H Eric, Mining And Metal Extraction In South Africa), Ahmet Deniz Bas

Ahmet Deniz Bas

No abstract provided.


Thermodynamic Analysis Of Rare Earth Chlorination And Bromination Processes, Katie Lyons, Jerome Downey, Dan Gaede, Bryce Ruffier 2015 Montana Tech of the University of Montana

Thermodynamic Analysis Of Rare Earth Chlorination And Bromination Processes, Katie Lyons, Jerome Downey, Dan Gaede, Bryce Ruffier

2015 Undergraduate Research

Research funded by the Army Research Laboratory (ARL), the Metallurgical and Materials Engineering Department at Montana Tech investigated various methods of extracting and refining rare earth elements (REEs) from mineral ores and concentrates. Extensive thermodynamic, thermogravimetric and differential thermal analyses were performed to evaluate the relative stabilities of various REE compounds in order to assess potential methods for selective separation and recovery of specific REEs. Conversion of rare earth oxides (REO) to rare earth chlorides or bromides is a possible initial step in pyrometallurgical and hydrometallurgical processing of REEs. REO can be converted to chlorides or bromides by roasting in ...


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