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Process-Structure Relationships Of Magnesium Alloys, Arindam Banerjee

University of Western Ontario - Electronic Thesis and Dissertation Repository

This research study characterizes the effects of solidification conditions on the resulting microstructure of an AM60B magnesium alloy during the solidification cycle of the casting. Seventeen control points are chosen from different sections of an instrument panel beam casting and its centerline coordinates are located. These control points locations are then used by Meridian Lightweight Technology Inc. to run a simulation in a MAGMASoft casting software to obtain temperature-time specific data.

An exact analytical solution to the Stefan problem is used to compute the one dimensional heat transfer for a section of the casting and to calculate its temperature distribution ...

Lignin Yield Maximization Of Lignocellulosic Biomass By Taguchi Robust Product Design Using Organosolv Fractionation, Anton Friedrich Astner

Masters Theses

Lignin, a byproduct of the organosolv pretreatment process using lignocellulosic biomass from switchgrass (Panicum virgatum) and tulip poplar (Liriodendron tulipifera) is currently being explored for its potential use in the production of value-added chemicals and biobased polymers. Pretreatment is one of the most expensive processing steps in cellulosic biomass conversion. Optimization of the process is one of the major goals of the biomass-toethanol conversion process. Taguchi Robust Product Design (TRPD) provides an effective engineering experimental design method for optimizing a system and designing products that are robust to process variations. Given the results of several preliminary studies of the organosolv ...

Understanding Size Effects In Small Scale Deformation: A Statistical Perspective, Sudharshan Phani Pardhasaradhi

Doctoral Dissertations

Recent experimental observations of micro-compression / tension tests indicate that as the size of test specimen decreases the yield strength increases. This raises a fundamental question: Why is smaller stronger? Is there a fundamental relationship between the size of a specimen and its intrinsic strength? This simple question pushes the limit of the current understanding of the physical mechanisms underlying material deformation, especially at small scales. In order to explain the experimental observations of the strength of small specimens containing a limited number of dislocations, a simple statistical model is developed. Two different types of randomness are introduced, viz., randomness in ...

Structure And Dynamics Of High Temperature Superconductors, Jennifer Lynn Niedziela

Doctoral Dissertations

High temperature superconductivity in iron based compounds has presented a series of complex problems to condensed matter physics since being discovered in 2008. The stalwart basis of condensed matter physics is the “strength in numbers" aspect of crystalline periodicity. Perfect crystalline periodicity has made possible the reduction of the questions of structural and electronic properties to single dimensions, increasing the tractability of these problems. Nevertheless, modern complex materials stretch these assumptions to their limits, and it is at this point where our work starts. Using neutron and x-ray scattering, we have conducted a series of studies on the structural disorder ...

Quantum Man, Julian Voss-Andreae

The STEAM Journal

According to quantum physics, the world is fundamentally quite different than it seems. Drawing inspiration from the underlying nature of reality, former quantum physicist Julian Voss-Andreae created an image of a walking human as a quantum object. Made up of parallel sheets of steel, the sculpture is a metaphor for the counter-intuitive world of quantum physics. Symbolizing the dual nature of matter with the appearance of classical reality on the surface and cloudy quantum behavior underneath, the sculpture seems to consist of solid steel when seen from the front, but dissolves into almost nothing when seen from the side.

Migration Grid #26, Stanton Hunter

The STEAM Journal

This work is inspired by invisible sky grids formed by Ultra Violet (UV) light researchers discovered that guide Monarch butterflies on their migration from the mid-western United States to the Sierra Madre Mountains in Mexico. I use terrestrial material, clay, to make something celestial. Earth, associated with mass and permanence, is translated into these shifting, ephemeral, and ethereal sky-forms. The work encompasses void more than object and the complex shadows they cast are immaterial. Together, the objects and shadows point to what can’t be seen, at least by the human eye.

Electrodeposition Of Co-Mn And Cu-Mn Based Spinels Onto Solid Oxide Fuel Cell Interconnects, Xavier D. Michaud Mr

Open Access Dissertations and Theses

Solid oxide fuel cells are an efficient method of converting hydrocarbon fuels to electrical power. However, due to some problems with poisoning, these have made no headway in the energy market. The evaporation of chromium oxides from metallic current collectors causes rapid degradation of the cells on the cathode side. It has been shown that spinel coatings reduce the effects of chromium oxide evaporation. In this thesis, two spinel systems are explored for potential application. Cobalt-manganese spinel is a stable spinel which have a wide range of composition, while remaining sufficiently conductive. Copper-manganese spinel, which is much more conductive than ...

Wolfpack Gear Inc. Composite Frame Firefighter Backpack, Gabriel Mountjoy, Blair Ridings, Carl Drummond Buchenroth

Mechanical Engineering

No abstract provided.

Analyzing The Corrosion Resistance Of Ni-Shield 200 Coatings At Different Temperatures When Exposed To Sulphuric Acid, Alex Hussinger

Materials Engineering

Six steel samples each were twin wire arc sprayed with Hastelloy C-276 or Nickel-Shield 200 coatings approximately 0.020″ thick. These samples were then cut into 3″ by 3″ squares. A 2″ diamond grit hole saw was used to abrade and polish to a smooth surface a ring in the middle in order to get an O-ring mechanical seal. The samples were then weighed and loaded into a jig that started from the bottom up with a stainless steel plate, then the sample, then a Viton O-ring, a ¾″ thick glass plate with a 1 3/4″ hole cut in ...

Magnetic And Elastic Properties Of Magnetostrictive Tb6fe1-Xcoxbi2, Michael Richard Koehler

Doctoral Dissertations

The Tb6[6 sub]Fe1-x[1-x sub]Cox[x sub]Bi2[2 sub] (x = 0, 0.125, 0.25, and 0.375) family of compounds has been synthesized and investigated for magnetostrictive behavior using capacitance dilatometry. These measurements have been complemented by measurements of the elastic moduli using Resonant Ultrasound Spectroscopy (RUS), magnetization measurements (with a vibrating sample magnetometer (VSM)), as well as powder X-ray diffraction (XRD) and powder neutron diffraction measurements and heat capacity measurements.

Each of the compounds studied shows little magnetostriction at the Curie temperature but shows pronounced amounts of magnetostriction at temperatures below 100 K. Magnetostriction ...

Pretreatment And Pyrolysis Of Rayon-Based Precursor For Carbon Fibers, Kokouvi Akato

Masters Theses

In this work, two rayon fibers were investigated as carbon fiber precursors. A detailed consideration has been applied to a domestically produced cellulose fiber to carbon fiber (CF) transition. This transition of precursor to carbon fiber can be subdivided into two stages: pyrolysis (thermal decomposition) of cellulose in air and high temperature treatment in an inert atmosphere. The specific objectives were to investigate the stabilization stage of the produced rayon with respect to changes taking place during thermal decomposition, and to evaluate the effects on the properties of the carbonized fiber. Changes taking place during the conversion process of the ...

Manganese Dioxide Based Composite Electrodes For Electrochemical Supercapacitors, Yaohui Wang

Open Access Dissertations and Theses

Advanced electrodes based on MnO₂ for the electrochemical supercapacitor (ES) application have been fabricated using electrochemical and chemical methods.

Electrosynthesis method has been utilized for the in-situ impregnation of manganese dioxide in commercial Ni plaque current collectors. Dipping-reduction, cathodic galvanostatic and reverse pulse electrosynthesis methods were investigated. The material loading was varied by the variation of the number of the dipping-reduction procedures in the chemical precipitation method or by the variation of charge passed in the electrochemical methods. The results obtained by different methods were compared. The dipping-reduction method offered the advantage of higher specific capacitances (SCs) at high ...

Structure, Surfaces, And Composition Of Catalytic Nanoparticles From Quantitative Aberration Corrected Transmission Electron Microscopy, Mickey Chan

Open Access Dissertations and Theses

Proton exchange membrane fuel cells (PEMFC) are a technology of high interest for the automotive and power generation industry. The catalyst layer plays a critical role in fuel cells as it is responsible for catalyzing hydrogen oxidation and oxygen reduction to generate electricity. The current challenge in catalyst development is to produce highly active and economical catalysts. This challenge cannot be overcome without an accurate understanding of catalyst surfaces and morphology since the catalytic reactions occur on the surface active sites. Transmission electron microscopy (TEM) is an excellent tool to understand the structures of the nanoparticles down to the atomic ...

Biaxial & Twist Testing Of Composite Carbon-Fiber Sandwich Panels For Automotive Racing Vehicles, Erik Eckberg

Materials Engineering

Composite sandwich panels were constructed with 4-ply plain weave carbon-fiber/epoxy face sheets in the 0^o/45^o/0^o/45^o orientation and 1/8^th inch Nomex honeycomb core. The panels were cut into 5-inch square test plates for mechanical testing. All testing was done on a fixture designed and fabricated by Pratt & Miller Engineering and installed on an Instron testing system at Cal Poly. The twist test was performed by supporting diagonal corners of the plate while simultaneously loading the opposite two corners at a crosshead rate of .06 in/min (ASTM 3044-94R11). Out of 10 panels tested, six were tested longitudinally, with the L direction of the honeycomb parallel to the front of the test plate, and four were tested in the transverse orientation, with the L direction of the honeycomb perpendicular to the front of the plate. The average compliance for the longitudinal loading was 1.303 mil/lb, and the transverse loading was 1.394 mil/lb. The panels failed with a combination core shear failure and face-to-core debonding. The anisotropic nature of the honeycomb core supports the difference in the compliance of the panels; however the complex loading of the twist test results the difference being not statistically significant. The biaxial bending tests involved supporting the composite plate on each corner and loading it in the center. In 5 tested plates, the measured average compliance was .4363 mil ...

Coatings For Corrosion Protection Of Metals And Alloys, Lijia Yang

Open Access Dissertations and Theses

Thin films prepared by electrochemical and physical vapor deposition (PVD) methods were investigated for corrosion protection of metals and alloys. Various electrochemical methods were developed, such as electrophoretic deposition (EPD), electrolytic deposition (ELD) and combined methods. EPD method has been developed for the deposition of polymer films, including poly(2-vinylpyridine) (PVP) and co-polymer poly(4-vinylpyridine-co-butyl methacrylate) (PVPBM). The method involved the electrophoresis of protonated polymer macromolecules, base generation at the cathode surface, charge neutralization and deposition of water insoluble polymer films. Nanostructured CeO₂ films were prepared by cathodic ELD and EPD. Cathodic ELD involved electrosynthesis of CeO ...

Blunt Impact Performance Evaluation Of Helmet Lining Systems For Military And Recreational Use, Jaclyn Siniora, Ryan Taylor, Darren Suey

Industrial Technology

With the increasing problem in collegiate athletes experiencing injuries to the brain, different helmet liners where put to the test to see which liner provided athletes the greatest protection under specific conditions.

This senior project evaluates five different liners in football helmets. Each of the helmet liners were tested at three different temperatures: hot, cold, and ambient. Each helmet had seven different impact locations which were put to the test. The project was designed to be used to test ACH military combat liners as well. Due to shipping bottle necks the ACH combat liners have been left to future Cal ...

Magnetic Properties Study Of The Mn-Al System With Additions Of B Or C And Mechanical Milling Techniques, Timothy E. Prost

Engineering Mechanics Dissertations & Theses

Recently a shift in the focus of permanent magnetic research has moved from Rare Earth (RE)-based alloys to those made from more readily available elements. Because of their relatively large magnetocrystalline anisotropy, L1₀ compounds have the potential for use as permanent magnet materials. One particular alloy that is readily available and inexpensive is near equi-atomic manganese and aluminum (Mn₅₀-Al₅₀). First characterized in 1958, it did not receive much attention until more recently when RE supply chain issues made the alloy more attractive for commercial and research applications. The ferromagnetic (FM) τ-phase (L1₀) is metastable ...

A Review Of Cutting-Edge Techniques For Material Selection, Noori Brifcani, Richard Day, David Walker, Suzanne Hughes, Ken Ball, Dave Price

Aeronautical Engineering

Selecting the optimum material for a given application is a complex task for engineers and designers across all industrial fields. There are a huge number of materials now available with a range of different properties and behaviours and so it has become even more necessary to carry out a systematic process in order to screen and/or rank the materials to give a promising number of candidates. The output of the material selection process depends upon which method is used. In some methods, a chart can be used to identify promising candidates whereas in others a single ‘optimum’ material may ...

Phase Field Crystal Approach To The Solidification Of Ferromagnetic Materials, Niloufar Faghihi

Electronic Thesis and Dissertation Repository

The dependence of the magnetic hardness on the microstructure of magnetic solids is investigated, using a field theoretical approach, called the Magnetic Phase Field Crystal model. We constructed the free energy by extending the Phase Field Crystal (PFC) formalism and including terms to incorporate the ferromagnetic phase transition and the anisotropic magneto-elastic effects, i.e., the magnetostriction effect. Using this model we performed both analytical calculations and numerical simulations to study the coupling between the magnetic and elastic properties in ferromagnetic solids. By analytically minimizing the free energy, we calculated the equilibrium phases of the system to be liquid, non-magnetic ...

Large Eddy Simulation (Les) Of Glass Fibre Dispersion In An Internally Spout-Fluidised Bed For Thermoplastic Composite Processing, Xiaogang Yang, Xiaobing Huang, Yuan Zong, Grance Dai

Aeronautical Engineering

Large eddy simulation (LES) has been conducted to investigate glass fibre dispersion in an internally spout-fluidised bed with draft tube and disk-baffle, which was used in the manufacture of long glass fibre reinforced thermoplastic composites. The LES results have demonstrated that the internally spout-fluidised bed with draft tube and disk-baffle can remarkably improve its hydrody-namic behaviour, which can effectively disperse fibre bundles and promote pre-impregnation with resin powder in manufacturing fibre reinforced thermoplastics. The hydrodynamics of the spout-fluidised bed has been investigated and reported in a previous paper (Hosseini et al., 2009). This study attempts to reveal important features of ...