Other Materials Science and Engineering Commons^™

The Effects Of Applied Strain And Heat Treatment On The Properties Of Niti Wire During Shape Setting, Frank Zapoticla

Master's Theses

NiTi components are commonly subjected to thermo-mechanical heat treatments during production and fabrication. This study investigates the effects of applied strain of 0-10% and heat treatments of 300-600ºC for times of 2-30 minutes during shape-setting of Ti–50.8 at% Ni wire with a nominal diameter of 0.495 mm and an initial transition temperature, Af, of 12ºC. Strain was applied prior to heat treatments by coiling NiTi wire, essentially producing coiled springs, around different diameter steel mandrels to obtain different strain levels. The samples of NiTi wire under applied strain were heat treated in a salt bath, followed by a rapid quench. …

Elastic And Magnetic Properties Of Tb6fe(Sb,Bi)2 Using Resonant Ultrasound Spectroscopy., David Michael Mccarthy

Masters Theses

Tb6FeSb2 and Tb6FeBi2 are novel rare earth compounds with little prior research. These compounds show high and variable curie temperatures for rare-earth compounds. This has lead to a literature review which includes the discussion of: elasticity, resonance, and magnetism. This review is used to discuss the theory and methodology which can relate these various properties to each other. Furthermore, synthesis, x-ray analysis, and RUS sample preparation of Tb6FeSb2 and Tb6FeBi2 were completed.

Resonant Ultrasound Spectroscopy (RUS) elastic studies were taken for Tb6FeSb2 and Tb6FeBi2 as a function temperature from 5-300K, in various magnetic fields ranging from 0-9T. Tb6FeSb2’s and Tb6FeBi2’s …

Structural And Magnetic Properties Of Neodymium - Iron - Boron Clusters, Jeremy J. Anderson

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Using inert gas condensation techniques the properties of sputtered neodymium-iron-born clusters were investigated. A D.C. magnetron sputtering source created vaporous Nd-Fe-B which was then condensed into clusters and deposited onto silicon substrates. A composite target of Nd-Fe-B discs on an iron plate and a composite target of Nd-(Fe-Co)-B were utilized to create clusters. The clusters were coated with a carbon layer through R.F. sputtering to prevent oxidation.

Samples were investigated in the TEM and showed a size distribution with an average particle diameter of 8.11 nm. The clusters, upon deposition, were amorphous as indicated by diffuse diffraction patterns obtained through …

Tribological Comparison Of Traditional And Advanced Firearm Coatings, Greg Boban

Master's Theses

The objective of this project is to find which type of coating has the best performance characteristics for finishing firearms. This is accomplished by measuring and comparing several performance characteristics, such as: adhesion, hardness, wear resistance, friction control, and corrosion resistance. Appearance is not a factor since any exterior coating that is flashy can be subdued or camouflaged with special purpose paints, which have proven durable enough for such purposes. Cost will not be a limiting factor for this experiment, but will be discussed in the conclusion as a secondary concern. This data will be used to identify the best …

Characterization Of Aluminum-Boron Carbide Particulate Metal Matrix Composites, Eric Blank

Materials Engineering

The analysis of die-cast 380 aluminum-boron carbide particulate metal matrix composites (MMC) was performed in order to see if the samples had the required tensile strength of 300 MPa. 10wt% B4C die-cast samples were produced and tested. Half were heat treated to the T6 condition and the others were left as cast. Using ASTM standard B 557M it was found that the average tensile strength for the as-cast samples was 130 MPa and the heat treated samples had a tensile strength of 93 MPa. These values were both lower than expected. The heat treated samples were not expected to have …

Validation Of A Secondary Fabric Supplier And Characterization Of Alternate Cores For Use In The Aptera 2e Sandwich Core Composite, Bryan Rogers

Materials Engineering

Polymer matrix composites’ high strength to weight ratio has made them an ideal material choice for use in lightweight transportation vehicles. Aptera Motors, a company based out of Oceanside, CA, is currently developing a next-generation high efficiency passenger vehicle called the Aptera 2e. The 2e’s body is composed of a sandwich core composite containing laminates of E-glass fibers embedded within an epoxy matrix sandwiched between a polyester hexagonal core. This project looked to validate a secondary fabric supplier for use in Aptera’s composite and characterize the core shear properties of two alternate core materials for future iterations of Aptera’s vehicle. …

The Characterization And Analysis Of In-Vitro And Elevated Temperature Repassivation Of Ti-6al-4v Via Afm Techniques, Aaron J. Guerrero

Master's Theses

ABSTRACT

The Characterization and Analysis of In-vitro and Elevated Temperature Repassivation of

Ti-6Al-4V via AFM Techniques

Aaron J Guerrero

Research in the corrosion of orthopaedic implants is a growing research field where implants have been known to show adverse effects in patients who have encountered the unfortunate dissolution of their implants due to corrosion. Once corrosion begins within the body, many adverse biological reactions can occur such as late on-set infections resulting in severe health complications. The focus of this research is specifically related to the problem of late on-set infections caused by localized corrosion of orthopaedic implants. In medical …

Optimisation Acoustique De Paroi Par Algorithme Génétique Et Influence De L’Habillage Par Une Couche Poreuse, Nicolas Dauchez, Olivier Doutres, Jean-Michel Genevaux, Jean-Christophe Le Roux

Olivier Doutres Ph.D.

L’amélioration du confort acoustique dans les habitacles passe en particulier par l’optimisation de la transparence acoustique de parois simple ou double au moyen de matériaux viscoélastiques et poreux. Une méthode d’optimisation de paroi basée sur un algorithme génétique couplé à un calcul par matrices de transfert est présentée. Cette technique permet une exploitation efficace des itérations précédentes sans coût de calcul supplémentaire. Les résultats obtenus pour une simple et une double paroi sont analysés. Dans un deuxième temps, l’influence d’un habillage poreux est présenté en fonction de la nature du squelette : mousse polymère ou fibreux. On montre, à l’aide …

Mesure Des Propriétés Mécaniques Des Matériaux Poreux À L’Aide D’Un Transducteur Électrodynamique Sans Fer, Nicolas Dauchez, Olivier Doutres, Jean-Michel Génevaux, Guy Lemarquand, Sylvain Mezil

Olivier Doutres Ph.D.

Un banc de mesure des propriétés mécaniques des matériaux poreux est présenté. Il permet d'étendre les méthodes quasistatiques basées sur la compression d'un échantillon vers les hautes fréquences. Les méthodes quasistatiques sont limitées en fréquence (< 100 Hz) parce qu'elles négligent les éléments inertiels et le couplage avec l'air ambiant. Dans la méthode présentée, l'échantillon est placé dans une cavité étanche pour limiter l'effet de l'air ambiant et ainsi permettre une meilleure estimation du facteur de perte. Un transducteur électrodynamique a été conçu spécifiquement pour permettre une excitation sur une large gamme de fréquence : les premiers modes de l'équipage mobile sont au dela de 5 kHz. De plus, son architecture sans fer et sans suspension viscoélastique permet de l'utiliser comme capteur par le biais de son impédance électrique. L'impédance mécanique de l'échantillon est obtenue en inversant le modèle électromécanique du transducteur et les propriétés viscoélastiques - module d'Young et facteur de perte - sont obtenues par recalage d'un modèle analytique utilisant la théorie de Biot-Allard. Les résultats sont présentés pour une mousse polymère à cellule ouvertes. Le calcul des incertitudes montre que la méthode permet une bonne estimation jusque 500 Hz et permet de définir les conditions d'extension de la plage de fréquence.

Characterization And Measurement Of Passive And Active Metamaterial Devices, Christopher A. Lundell

Theses and Dissertations

This document addresses two major obstacles facing metamaterial development: uncertainty in the characterization of electromagnetic field behavior in metamaterial structures and the relatively small operational bandwidth of metamaterial structures. To address the first obstacle, a new method to characterize electromagnetic field behavior in a metamaterial is presented. This new method is a bistatic radar cross section (RCS) measurement technique. RCS measurements are well-suited to measuring bulk metamaterial samples because they show frequency dependence of scattering angles and offer common postprocessing techniques that can be useful for visualizing results. To address the second obstacle, this document characterizes the effectiveness of an …

Optical And Electrical Characterization Of Bulk Grown Indium-Gallium-Arsenide Alloys, Austin C. Bergstrom

Theses and Dissertations

Advances in crystal growth techniques have allowed increased quality in growth of bulk ternary In_xGa_1-xAs. Here, the optical and electrical properties of samples grown through the vertical Bridgman (or multi-component zone melting growth) method have been investigated through photoluminescence spectroscopy and Hall effect measurements. Indium mole fractions varied from 0.75 for 1. Hall effect measurements at temperatures ranging from 10 to 300 K revealed moderate n-type doping with carrier concentrations ranging from 1.5 to 9.6×10¹⁶ cm^-3 at 10 to 15 K. Carriers from deep donor levels became appreciable between 50 and 100 K. Hall …

Time-Temperature Curing Relationship Of An Adhesive Binder With Rice Straw, Kevin Ka-Wan Ng

Master's Theses

Rice straw is a global and proliferate agricultural waste whose production grossly outstrips viable uses. Current disposal methods are not sustainable, and more convenient methods – such as incineration – exude poor environmental stewardship. Although the direct use of straw bales in building construction presents a practical and sustainable alternative, engineering challenges associated with using it prevent its wide adoption. The Stak Block – a composite formed from compressed rice straw and a heat-cured adhesive – may overcome challenges associated with straw bale building. However, the times and temperatures needed to cure the binder with straw are not well understood. …

[Ni(Tmen)(Acac)][B(Ph)4] A Probe For The Anion Basicity Of Ionic Liquids, Joanna Bartosik, Anja V. Mudring

Anja V. Mudring

An optical basicity scale of various ionic liquids (IL) anions has been determined by UV-Vis absorption spectroscopy. The indicator complex [Ni(tmen)(acac)][B(Ph)4] (tmen = tetramethylethylendiamine, acac = acetylacetonate) shows to be a sensitive probe as the position of the 3A2g(F) → 3T1g(F) absorption maximum of square planar to octahedral Ni2+ shifts distinctly depending on the electron donor ability of the respective ionic liquid anion. If the Lewis basicity of the anion becomes stronger a change to a tetrahedral coordination around Ni2+ is observed. Here the 3T1(F) → 3T2(F) and 3T1(F) → 3T1(P) transitions are helpful for monitoring the IL anion basicity. …

On The Dissolution Of Non-Metallic Solid Elements (Sulfur, Selenium, Tellurium And Phosphorus) In Ionic Liquids, Eva Boros, Martyn J. Earle, Manuela A. Gilea, Andreas Metlen, Anja V. Mudring, Franziska Rieger, Allan J. Robertson, Kenneth R. Seddon, Alina A. Tomaszowska, Lev Trusov, Joseph S. Vyle

Anja V. Mudring

Ionic liquids are shown to be good solvents for elemental sulfur, selenium, phosphorus and tellurium, and can be designed to maximise the solubility of these elements. The presence of the [S3]˙− radical anion in diluted solutions of sulfur in some ionic liquids has been confirmed, and is the origin of their intense blue colour (cf. lapis lazuli).

Communication Prev. Article Next Article Table Of Contents Chains Of Face-Sharing {Zpr6} Octahedra With Alternating Endohedral Iridium Atoms And Chloride Ions In {(Ir,Cl)Pr6}Cl10, Nina Herzmann, Matthias Bruhmann, Anja V. Mudring, Gerd Meyer

Anja V. Mudring

The most impressive feature of the crystal structure of IrPr6Cl11 is chains of face-sharing {Pr6} octahedra that encapsulate, alternatingly, iridium atoms and chloride ions, according to the formulation {(Ir,Cl)Pr6}Cl10. An alternative description of the structure is the connection of isolated {IrPr6} clusters that are surrounded in a mixed {ZR6}Xi12/{ZR6}Xi8 type by chlorido ligands with a rather complex connectivity, {IrPr6}(Cli−a−a4/3Cla−i−a8/3Cli−a6/2Cla−i6/2)e(Cli−i2/2)f, to a three-dimensional structure of tetragonally packed cluster-complex chains.

Facile Preparation Of Quantum Cutting Gdf3 : Eu3+ Nanoparticles From Ionic Liquids, Chantal Lorbeer, Joanna Cybinska, Anja V. Mudring

Anja V. Mudring

Microwave reaction of Ln(OAc)3·xH2O, Ln = Gd, Eu; OAc = acetate) with and in the ionic liquid [C4mim][BF4] (C4mim = 1-butyl-3-methylimidazolium) allows the fast and efficient synthesis of small, uniform, oxygen-free lanthanide nanofluorides with excellent photophysical behaviour. For GdF3 : Eu3+ nanoparticles a quantum efficiency of up to 145% was determined.

Electronic And Magnetic Structure Of (Crcl 3 ) 3, M. Grodzicki, B. Mallick, Anja V. Mudring

Anja V. Mudring

Electronic structure calculations in the local spin-density approximation have been carried out on the recently synthesized trimer (CrCl 3 ) 3 exhibiting antiferromagnetic ordering below T N =55 K. The calculated magnetic coupling constant, the paramagnetic Curie temperature, and the decrease of the magnetic moment below T N are well reproduced by the calculations. An interpretation of the spin structure is given that is consistent with all experimental data currently available.

Optical Basicity Of Ionic Liquids, Slawomir Pitula, Anja V. Mudring

Anja V. Mudring

The concept of optical basicities initially developed by Duffy for solid oxides was successfully transferred to low melting salts such as ionic liquids (ILs). Several ionic liquids (ILs) were doped with Mn(NTf2)2 (NTf2 = bis(trifluoromethanesulfonyl)imide) as a probe to investigate the IL anion basicity by means of UV-Vis spectroscopy. The 6A1 → 4A, 4E(G) transition band of Mn2+ is influenced by the electron donor properties, i.e., Lewis basicity, of the coordinating ligands but remains—to the first order—independent from the ligand field. The change in the optical spectra for various Mn(NTf2)2 doped ILs is predominantly dependent on the anion. No significant …

Electrostatic Quadrupole Plasma Mass Spectrometer Measurements During Thin Film Depositions Using Simultaneous Matrix Assisted Pulsed Laser Evaporation And Magnetron Sputtering, Chad N. Hunter, Michael H. Check, Christopher Muratore, Andrey A. Voevodin

Chemical and Materials Engineering Faculty Publications

A hybrid plasma deposition process, combining matrix assisted pulsed laser evaporation (MAPLE) of carbon nanopearls (CNPs) with magnetron sputtering of gold was investigated for growth of composite films, where 100 nm sized CNPs were encapsulated into a gold matrix. Composition and morphology of such composite films was characterized with x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM) analysis. Carbondeposits on a gold magnetron sputter target and carbon impurities in the gold matrices of depositedfilms were observed while codepositing from gold and frozen toluene-CNP MAPLE targets in pure argon. Electrostatic quadrupole plasma analysis was used to determine that …