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Articles 4921 - 4950 of 16707

Full-Text Articles in Engineering

Sound, Material And Strength Correlation, Ryan Mcbride May 2021

Sound, Material And Strength Correlation, Ryan Mcbride

Symposium of Student Scholars

With a growing amount of manufacturing utilizing 3D printing, there is a correlation between strength and material which can affect sound produced by sirens. An air raid siren that has been downloaded from Thingiverse.com spins with a 49:1 gear ratio to produce 2 tone sounds and with that large number of revolutions comes friction, and in order to create a 3D printed air raid siren, the siren must be made out of a material that can withstand high temperatures without melting and quick rotations without delaminating. There are many materials that can be printed to withstand those forces, but it …


Experimental Investigation Of Surface Resistivity Of Yttrium Stabilized Zirconium As A Thin Film, Matthew J. Melfi May 2021

Experimental Investigation Of Surface Resistivity Of Yttrium Stabilized Zirconium As A Thin Film, Matthew J. Melfi

Seton Hall University Dissertations and Theses (ETDs)

Solid Oxide Fuel Cells are devices that use electrochemical reactions to convert chemical energy from fuel to electricity. In comparison with coal power plants, a Solid Oxide Fuel Cell, produces a higher electrical conversion efficiency. However, at higher temperatures (1000°C) it creates a lower ionic conductivity, which limit the Solid Oxide Fuel Cells. When lowering the temperature, the ohmic resistance increases. In our research, an Yttrium Stabilized Zirconium layer will be produced from a fine dimple grain structure allowing high flow of oxygen mobility. This mobility increases ionic conductivity and decrease ohmic loss. The goal of our research is first …


Ph-Responsive Oxygen/Glucose Delivery System To Increase Cell Survival Under Ischemia, Yubin Ying May 2021

Ph-Responsive Oxygen/Glucose Delivery System To Increase Cell Survival Under Ischemia, Yubin Ying

McKelvey School of Engineering Graduate Student Theses & Dissertations

Ischemic diseases, including myocardial infarction, stroke and limb ischemia, are life-threatening vascular diseases with high mortality. Under ischemic condition, less blood supply causes insufficient oxygen and nutrients transported to the affected tissues, which leads to cell death. To support cell survival under ischemia, oxygen and nutrients (especially glucose) are needed for aerobic respiration to generate energy. Therefore, directly supplying oxygen and glucose to the ischemic tissues is a promising therapy for ischemic diseases. In this work, we aim to design biomaterials to deliver oxygen and glucose to enhance cell survival under ischemia. In the first project, we fabricated oxygen releasing …


Open Source Vacuum Oven Design For Low-Temperature Drying: Performance Evaluation For Recycled Pet And Biomass, Benjamin R. Hubbard, Lindsay I. Putman, Stephen Techtmann, Joshua M. Pearce May 2021

Open Source Vacuum Oven Design For Low-Temperature Drying: Performance Evaluation For Recycled Pet And Biomass, Benjamin R. Hubbard, Lindsay I. Putman, Stephen Techtmann, Joshua M. Pearce

Michigan Tech Publications, Part 1

Vacuum drying can dehydrate materials further than dry heat methods, while protecting sensitive materials from thermal degradation. Many industries have shifted to vacuum drying as cost-or time-saving measures. Small-scale vacuum drying, however, has been limited by the high costs of specialty scientific tools. To make vacuum drying more accessible, this study provides design and performance information for a small-scale open source vacuum oven, which can be fabricated from off-the-shelf and 3-D printed components. The oven is tested for drying speed and effectiveness on both waste plastic polyethylene terephthalate (PET) and a consortium of bacteria developed for bioprocessing of terephthalate wastes …


Computational Design Of Nonlinear Stress-Strain Of Isotropic Materials, Askhad M.Polatov, Akhmat M. Ikramov, Daniyarbek Razmukhamedov May 2021

Computational Design Of Nonlinear Stress-Strain Of Isotropic Materials, Askhad M.Polatov, Akhmat M. Ikramov, Daniyarbek Razmukhamedov

Chemical Technology, Control and Management

The article deals with the problems of numerical modeling of nonlinear physical processes of the stress-strain state of structural elements. An elastoplastic medium of a homogeneous solid material is investigated. The results of computational experiments on the study of the process of physically nonlinear deformation of isotropic elements of three-dimensional structures with a system of one- and double-periodic spherical cavities under uniaxial compression are presented. The influence and mutual influence of stress concentrators in the form of spherical cavities, vertically located two cavities and a horizontally located system of two cavities on the deformation of the structure are investigated. Numerical …


Rehology And Electrical Conductivity Of Particulate Composites In Additive Manufacturing, Bin Xia May 2021

Rehology And Electrical Conductivity Of Particulate Composites In Additive Manufacturing, Bin Xia

Mechanical Engineering Research Theses and Dissertations

Extrusion-based multi-functional additive manufacturing (AM) has been a rapidly developing area in AM recently. Particulate composites are widely used in this area to provide different functionalities with different types of particulate additives. However, there is no systematic understanding of the behavior of particulate composites during extrusion (especially in small nozzles) or of their properties once deposited in the build. This work investigates the properties of the type of particulate composites usually used in additive manufacturing, composed of a polymer matrix material and particulate additives within the micrometer scale. The focus is on the material rheology in the nozzle/capillary (for the …


Aerosol Vapor Synthesis Of Organic Processable Pedot Particles And Measuring Electric Conductivity Using A 3d Printed Probe Station, Yang Lu May 2021

Aerosol Vapor Synthesis Of Organic Processable Pedot Particles And Measuring Electric Conductivity Using A 3d Printed Probe Station, Yang Lu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Conducting polymers are organic semiconductors characterized by conjugated backbones (alternating single-double bonds) that enable mixed ionic-electronic conductivity. Their polymeric nature, tunable band structure and reversible redox capability have demonstrated fundamental advances in the fields ranging from electrochemical energy storage, sensing, to electro/photo catalysis and neuromorphic engineering. Conjugated backbones, the origin of all the unique physical and chemical properties associated with conducting polymers, prevent their solubility due to high lattice energy which hinders processing. Current solution utilizes a long-chain polymer (PSS) as dopants to render conducting polymer water dispersible (PEDOT:PSS). Nonetheless, PSS is highly acidic and hydrophilic limiting applicability with acid-incompatible …


Converting Inorganic Rust To Organic Nanostructured Conducting Polymers: Synthesis And Applications, Yifan Diao May 2021

Converting Inorganic Rust To Organic Nanostructured Conducting Polymers: Synthesis And Applications, Yifan Diao

McKelvey School of Engineering Graduate Student Theses & Dissertations

Iron rust is a type of corrosion product, coming from the chemical reaction between iron and oxygen in the presence of water that first documented ca. 800 BCE. It is a heterogeneous inorganic solid-state material composed of multiple phases and is ubiquitous throughout the universe. Rust species such as Hematite (α-Fe2O3), Akaganeite (β-FeOOH), and ferrous hydroxide (Fe(OH)2), make up the solid-state chemical family composed of iron oxides, oxyhydroxides, and hydroxides that are typically recognized as chemical waste. Conducting polymer is a type of organic plastic composed of long chains with repeating subunits that bonding with strong interactions between neighboring molecules. …


Rational Design And Optimization Of Perovskite Semiconductors, Arashdeep Thind May 2021

Rational Design And Optimization Of Perovskite Semiconductors, Arashdeep Thind

McKelvey School of Engineering Graduate Student Theses & Dissertations

ABSTRACT OF THE DISSERTATIONRational design and optimization of perovskite semiconductors by Arashdeep Singh Thind Doctor of Philosophy in Materials Science and Engineering Washington University in St. Louis, 2021 Professor Rohan Mishra, Chair

Lead-halide perovskites have emerged as a promising class of semiconductors for next-generation solar cells and optoelectronic devices. Since the report of the photovoltaic effect in 2009 in CH3NH3PbBr3 and CH3NH3PbI3, the power conversion efficiency of these perovskites has rapidly approached 25.2% from 3.8%. These perovskite semiconductors can be synthesized using low-cost solution-based techniques, unlike traditional semiconductors that require slow and expensive growth techniques to reduce the formation of …


Plasmonically-Enhanced Ultrasensitive Biodetection Technologies, Zheyu Wang May 2021

Plasmonically-Enhanced Ultrasensitive Biodetection Technologies, Zheyu Wang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Detection and quantification of biomolecules within biological fluids and tissues is of fundamental importance to biomedical research and clinical diagnostics. It is impossible to fully characterize complex, non-linear, biochemical systems without being able to accurately and quantitatively determine the component molecules. This problem is ubiquitous across all domains of biomedical research, and it is a major barrier to fully understanding health, ageing, and disease. Such bottlenecks are extremely challenging to be solved, especially for proteins and peptides, which do not have amplification schemes such as polymerase chain reaction for nucleic acids, because relevant concentrations of molecules related to diseases such …


Lagrangian Diffusion Properties Of A Free Shear Turbulent Jet, Bianca F. Viggiano, Thomas Basset, Stephen Solovitz, Thomas Barois, Mathieu Gibert, Nicolas Mordant, Laurent Chevillard, Romain Volk, Mickael Bourgoin, Raul Bayoan Cal May 2021

Lagrangian Diffusion Properties Of A Free Shear Turbulent Jet, Bianca F. Viggiano, Thomas Basset, Stephen Solovitz, Thomas Barois, Mathieu Gibert, Nicolas Mordant, Laurent Chevillard, Romain Volk, Mickael Bourgoin, Raul Bayoan Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

A Lagrangian experimental study of an axisymmetric turbulent water jet is performed to investigate the highly anisotropic and inhomogeneous flow field. Measurements are conducted within a Lagrangian exploration module, an icosahedron apparatus, to facilitate optical access of three cameras. Stereoscopic particle tracking velocimetry results in three-component tracks of position, velocity and acceleration of the tracer particles within the vertically oriented jet with a Taylor-based Reynolds number Reλ≃230. Analysis is performed at seven locations from 15 diameters up to 45 diameters downstream. Eulerian analysis is first carried out to obtain critical parameters of the jet and relevant scales, namely the Kolmogorov …


Exploration Of The Sludge Biodiesel Pathway, Zachary Christman May 2021

Exploration Of The Sludge Biodiesel Pathway, Zachary Christman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Wastewater sludge is an overlooked source of fat, oil, and grease (FOG) that could be converted into biodiesel. The United States produces about 8 million tons of sludge per year. The disposal cost for this amount of sludge is about 2 billion US dollars. The widespread availability and low cost of sludge compared to other biodiesel raw materials make it an economical choice for a renewable fuel. Using sludge as a raw material can produce 25 to 30 mg per gram of fatty acid methyl ester (FAME); the main component of biodiesel. Sludge biodiesel has the potential of transforming a …


Device Development For Long-Term Systemic Oral Biologic Drug Delivery, Benjamin Wankum May 2021

Device Development For Long-Term Systemic Oral Biologic Drug Delivery, Benjamin Wankum

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

A biologic drug is a drug that is produced by a living organism. Biologic drugs are used to treat various medical conditions such as arthritis, diabetes, or certain forms of cancers due to their high potency and high selectivity of action. Drawbacks of biologics include their poor stability in the gastrointestinal tract and their poor absorption. In effect, this gives the drugs very low bioavailability and short therapeutic half-lives. To combat these obstacles, current delivery methods include subcutaneous injections at home or intravenous or intramuscular injections in a medical facility.

The overall scientific goal of the research was to utilize …


Higher-Order Topolectrical Semimetal Realized Via Synthetic Gauge Fields, Xiang Ni, Andrea Alù May 2021

Higher-Order Topolectrical Semimetal Realized Via Synthetic Gauge Fields, Xiang Ni, Andrea Alù

Advanced Science Research Center

Classical bosonic systems may be tailored to support topological order and unidirectional edge transport exploiting gauge fields. Here, we theoretically explore how synthetic gauge fields may be used to induce higher-order topological phases and zero-energy boundary states. We demonstrate these principles in two types of three-dimensional topolectrical circuits with synthetic gauge fields threading through their reduced two-dimensional lattices, leading to a half-quantized quadrupole charge within a region of the momentum space. We theoretically show the emergence of nodal line rings and Weyl points in the bulk dispersion, whose projected surfaces and hinges support surface Fermi arcs and flat hinge Fermi …


Supporting Materials From The Program "Development Of A Physically-Based Creep Model Incorporating Eta Phase Evolution For Nickel Base Superalloys", N. R. Mohale, C. L. White, P. G. Sanders, W. W. Milligan, J. P. Shingledecker, P. A. Bridges May 2021

Supporting Materials From The Program "Development Of A Physically-Based Creep Model Incorporating Eta Phase Evolution For Nickel Base Superalloys", N. R. Mohale, C. L. White, P. G. Sanders, W. W. Milligan, J. P. Shingledecker, P. A. Bridges

Michigan Tech Research Data

This research was funded by the US Department of Energy, Fossil Energy Program, Grant Number DE-FE0027822, with Omer Bakshi as the Program Manager. The grant conditions required that all supporting data and materials would be made publicly-available. This public repository was created on May 13, 2021.


Multi-Scale Computational Modeling Of Metal/Ceramic Interfaces, Abu Shama Mohammad Miraz May 2021

Multi-Scale Computational Modeling Of Metal/Ceramic Interfaces, Abu Shama Mohammad Miraz

Master's Theses

Multi-scale atomistic calculations were carried out to understand the interfacial features that dictate the mechanical integrity of the metal/ceramic nanolaminates. As such, first principles density functional theory (DFT) calculations were performed to understand the electronic and atomistic factors governing adhesion and resistance to shear for simple metal/ceramic interfaces, whereas molecular dynamics (MD) simulations were performed to observe the impact of interfacial structures, such as misfit dislocation network geometries and orientation relationships, on interfacial mechanical properties.

For the DFT investigation, we choose metals with different crystal structures, namely - Cu (fcc), Cr (bcc) and Ti (hcp) along with a variety of …


Atomic Oxygen Resistant Low Earth Orbit Stable Polymer Matrix Composites Employing Phenylphosphine Oxide Epoxy-Amines, Witold Fuchs May 2021

Atomic Oxygen Resistant Low Earth Orbit Stable Polymer Matrix Composites Employing Phenylphosphine Oxide Epoxy-Amines, Witold Fuchs

Dissertations

Atomic oxygen (AO) attacks polymer matrix composites (PMC’s) on the surfaces of spacecraft in low earth orbit (LEO) and threatens safe spacecraft operation and service life. Incorporating phenylphosphine oxide (PPO) groups into polymer chains offers a self-regenerating method of protection from AO but remains poorly understood. Herein, epoxies containing PPO groups were synthesized with increasing concentrations of phosphorus [P] from 0 to 8 wt % to investigate their AO resistance. Measurements confirmed the exposure of these materials to AO produces a passivation phosphate (POx) layer on the surface of the sample and the efficacy of the resultant layer was directly …


Voltage-Controlled Magnetic Anisotropy In Antiferromagnetic Mgo-Capped Mnpt Films, P. H. Chang, Wuzhang Fang, T. Ozaki, Kirill Belashchenko May 2021

Voltage-Controlled Magnetic Anisotropy In Antiferromagnetic Mgo-Capped Mnpt Films, P. H. Chang, Wuzhang Fang, T. Ozaki, Kirill Belashchenko

Kirill Belashchenko Publications

The magnetic anisotropy in MgO-capped MnPt films and its voltage control are studied using first-principles calculations. Sharp variation of the magnetic anisotropy with film thickness, especially in the Pt-terminated film, suggests that it may be widely tuned by adjusting the film thickness. In thick films the linear voltage control coefficient is as large as 1.5 and -0.6 pJ/Vm for Pt-terminated and Mn-terminated interfaces, respectively. The combination of a widely tunable magnetic anisotropy energy and a large voltage-control coefficient suggest that MgO-capped MnPt films can serve as a versatile platform for magnetic memory and antiferromagnonic applications.


Design And Fabrication Of A Microstrip Bandpass Filter In Ltcc, Allison Rucker May 2021

Design And Fabrication Of A Microstrip Bandpass Filter In Ltcc, Allison Rucker

Electrical Engineering Undergraduate Honors Theses

The goal of the project was to design and fabricate a bandpass filter with a center frequency of 25GHz with a 2GHz bandwidth. The first step was to do the calculation to design a bandpass filter to meet these specifications along with the properties of the DupontTM GreenTapeTM 9K7. HFSS was then used to verify the results from the initial calculations. There was a significant error between the two results, so more tweaking was done to the calculations to get a better center frequency. After a final design was decided, the fabrication process started. Low-Temperature Co-Fired Ceramics (LLTC) …


An Investigation Of Testing Parameters On The Frictional Properties Of Patterned Core-Shell Nanostructures, Colin Phelan May 2021

An Investigation Of Testing Parameters On The Frictional Properties Of Patterned Core-Shell Nanostructures, Colin Phelan

Graduate Theses and Dissertations

Friction tests are a beneficial means to analyze the tribological characteristics and advantages of materials and textured surfaces. However, the selected test parameters can significantly influence the results. This work explores the significance of the friction testing parameters on the frictional performances of core-shell nanostructure-textured surfaces (CSNTSs). Several applied normal loads (10 μN, 100 μN, and 500 μN) and diamond counterface indenter tip radii (1 μm, 5 μm, and 20 μm) were selected for the testing of Al/diamond-like-carbon (DLC) and Al/amorphous silicon (a-Si) CSNTSs. The measured friction values of the CSNTSs were then compared to a matching Al/DLC film and …


A 3d Sers Device For Highly Sensitive Detection Of Organic Chemicals In Liquid, Sankgeeth Vennila Sigamani May 2021

A 3d Sers Device For Highly Sensitive Detection Of Organic Chemicals In Liquid, Sankgeeth Vennila Sigamani

Material Science and Engineering Theses - Archive

Detection of organic chemicals in liquid medium have been gaining utmost attention in recent times. Real time detection and monitoring of a variety of environmental pollutants, explosive materials, chemical agents, and pharmaceutical drugs in liquid medium are of great need in today’s technological advancements. While there are several scattering, emission and spectroscopy techniques in use, Raman spectroscopy is attractive because of its molecular specificity i.e., each molecule has a Raman fingerprint. Raman spectroscopy utilizes the inelastic portion of the scattered wave for detection. But since intensity of inelastic scattering (Raman scattering) is very low, compared to the elastic scattering, low …


Characterization Of Asphalt/Recycled Plastic Blends Modified By Exfoliated Clay Nanoplatelets, Kate A. Nguyen May 2021

Characterization Of Asphalt/Recycled Plastic Blends Modified By Exfoliated Clay Nanoplatelets, Kate A. Nguyen

Material Science and Engineering Theses - Archive

There is a renewed interest from federal and state transportation agencies as well as the asphalt industry in developing successful utilization of recycled plastics in asphalt pavements. By incorporating a third material into the asphalt/plastic blend, a stimulation of enhanced compatibility between the waste plastics and asphalt can be observed. In this thesis, the need for increased stability and improved mechanical performance of asphalt blends, at low and high temperatures, are addressed through the use of dispersed/exfoliated organic montmorillonite nanoplatelets a.k.a. nanoclay (NC). Previous studies with non-dispersed NC as a modifier in asphalt (AS) and polyethylene (PE) blends reported the …


Study Of Electromigration Failure Mechanism In Micro Solder Joint, Hossein Madanipour May 2021

Study Of Electromigration Failure Mechanism In Micro Solder Joint, Hossein Madanipour

Material Science and Engineering Dissertations - Archive

The miniaturizing trend for advanced electronic devices has motivated the microelectronic industries to pursue device integration and packaging technology based on the micro-bump solder joint. This type of the joint enables devices with far higher interconnect density and miniaturized form factors which are ideal for mobile applications. The focus of this research is to conduct comprehensive investigation on the electromigration (EM) reliability of micro solder joint. For that purpose, a series of EM tests on micro solder joints under direct current (DC) load was conducted with variation in the contributing factors to EM failure, including solder joint arrangement (change of …


Metal Nanodendrites And Their Applications As 3d Surface Enhanced Scattering (Sers) Substrates, Aseem Athavale May 2021

Metal Nanodendrites And Their Applications As 3d Surface Enhanced Scattering (Sers) Substrates, Aseem Athavale

Material Science and Engineering Dissertations - Archive

Ultrasensitive detection of chemicals and biological analytes has been a focus of a lot of studies in the recent years. In this search for the versatile detection technique, Surface Enhanced Raman Spectroscopy (SERS) has proved to be one powerful method. SERS is a powerful vibrational spectroscopy technique that allows for label free ultrasensitive detection. This method utilizes the Localized Surface Plasmon resonance (LSPR) effect of nanoparticles. LSPR effect is profound in noble metals such as silver (Ag) and gold (Au). We have developed a novel SERS substrate using Ag dendrites that can be applied as a ready-to-use device in a …


Multi-Scale Computational Modeling Of Metal/Ceramic Interfaces, Abu Shama Mohammad Miraz May 2021

Multi-Scale Computational Modeling Of Metal/Ceramic Interfaces, Abu Shama Mohammad Miraz

Doctoral Dissertations

Multi-scale atomistic calculations were carried out to understand the interfacial features that dictate the mechanical integrity of the metal/ceramic nanolaminates. As such, first principles density functional theory (DFT) calculations were performed to understand the electronic and atomistic factors governing adhesion and resistance to shear for simple metal/ceramic interfaces, whereas molecular dynamics (MD) simulations were performed to observe the impact of interfacial structures, such as misfit dislocation network geometries and orientation relationships, on interfacial mechanical properties.

For the DFT investigation, we choose metals with different crystal structures, namely - Cu (fcc), Cr (bcc) and Ti (hcp) along with a variety of …


Comparison Of Tensile Properties Of Triaxial Braided Carbon Fiber Composites Made From Vacuum Assisted Resin Transfer Molding (Vartm) And Autoclave Molding, Donald A. Klosterman, Charles Browning May 2021

Comparison Of Tensile Properties Of Triaxial Braided Carbon Fiber Composites Made From Vacuum Assisted Resin Transfer Molding (Vartm) And Autoclave Molding, Donald A. Klosterman, Charles Browning

Chemical and Materials Engineering Faculty Publications

Triaxially braided fiber composites are increasingly being used in aerospace, ballistic, and sporting good applications due to their inherent damage tolerance, torsional stability, and cost compared to woven fabrics and unidirectional preforms. There have been numerous publications over the past 15-20 years on the mechanical properties and failure mechanisms of triaxial braided composites. However, most of these have involved panels made with autoclave curing. In the present study, braided carbon fiber composites were made using autoclave curing and vacuum assisted resin transfer molding (VARTM). The goal of the study was to compare the physical and tensile properties of quasi-isotropic panels …


Effects Of Static Mixer Geometry On Polyurethane Properties, Christian R. Dixon May 2021

Effects Of Static Mixer Geometry On Polyurethane Properties, Christian R. Dixon

Honors Theses

The field of additive manufacturing has gained significant academic interest in the past few decades with a recently developed type of three-dimensional (3D) printing. Reactive extrusion additive manufacturing combines precursor materials within a static mixer (SM) head, where polymerization begins before deposition. Variable static mixer geometries currently exist, but the relationship between mixer geometry and post-polymerization mechanical properties is undefined. To elucidate this relationship, a series of experiments with identical chemistry was performed using a high shear SM, a low shear SM, and a comparative batch reaction. While higher shear mixing trends with faster polymerization for step-growth polymerizations, consistent precursor …


Utilizing The Oxygen-Barrier Properties Of Poly(Isobutylene) To Enhance Photon Upconversion In Thermoplastic Elastomers, Haley Carroll May 2021

Utilizing The Oxygen-Barrier Properties Of Poly(Isobutylene) To Enhance Photon Upconversion In Thermoplastic Elastomers, Haley Carroll

Honors Theses

Upconversion (UC) is the conversion of low energy light to higher energy light. It is utilized for a broad range of applications such as solar energy harvesting, microscopy of cellular biology, and cancer therapy. Specifically, triplet-triplet annihilation UC (TTA-UC) involves two dye species, a sensitizer and an annihilator, which are capable of upconverting noncoherent light such as sunlight. Traditionally, TTA-UC is achieved in solution, rubbers, or glasses, however, this work probes the capabilities of a thermoplastic elastomer (TPE) matrix to examine the effect of phase-separated morphology on the energy transfers necessary for TTA-UC. The system herein consists of poly(styrene-isobutylene-styrene) (SIBstar) …


Steam Oxidation Of Ytterbium Disilicate Environmental Barrier Coatings With And Without A Silicon Bond Coat, Ken A. Kane, Eugenio Garcia, Sharon Uwanyuze, Michael Lance, Kinga A. Unocic, Sanjay Sampath, Bruce A. Pint May 2021

Steam Oxidation Of Ytterbium Disilicate Environmental Barrier Coatings With And Without A Silicon Bond Coat, Ken A. Kane, Eugenio Garcia, Sharon Uwanyuze, Michael Lance, Kinga A. Unocic, Sanjay Sampath, Bruce A. Pint

Materials Science and Engineering Faculty Research & Creative Works

The current generation of multilayer Si/Yb2Si2O7 environmental barrier coatings (EBCs) are temperature limited by the melting point of Si, 1414°C. To investigate higher temperature EBCs, the cyclic steam oxidation of EBCs comprised of a single layer of ytterbium disilicate (YbDS) was compared to multilayered Si/YbDS EBCs, both deposited on SiC substrates using atmospheric plasma spray. After 500 1-h cycles at 1300°C in 90 vol%H2O-10 vol%air with a gas velocity of 1.5 cm/s, both multilayer Si/YbDS and single layer YbDS grew thinner silica scales than bare SiC, with the single layer YbDS forming the …


Study Of Static And Dynamical Properties Of Complex Antiferroelectrics Materials, Kinnary Yogeshbhai Patel May 2021

Study Of Static And Dynamical Properties Of Complex Antiferroelectrics Materials, Kinnary Yogeshbhai Patel

Graduate Theses and Dissertations

The aim of this dissertation is the investigation of the static and dynamical properties of the complex antiferroelectric materials using Effective Hamiltonian method and First principles calculations. In chapter 3, a novel elemental interatomic coupling in perovskite materials which bilinearly couples the antiferroelectric displacements of cations with the rotations of the oxygen octahedra. This new coupling explains a very complex crystal structure of prototypical antiferroelectric PbZrO3. My explanation provides a unified description of many other complex antipolar crystal structures in variety of perovskite materials, including the occurrence of incommensurate phases in some of them. In chapter 4, results and analysis …