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Graduate Theses and Dissertations

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Full-Text Articles in Engineering Science and Materials

Study Of Combustion Performance Of Al/Ptfe B/Ptfe And B/Al/Ptfe Composites, Liyun Feng Jan 2019

Study Of Combustion Performance Of Al/Ptfe B/Ptfe And B/Al/Ptfe Composites, Liyun Feng

Graduate Theses and Dissertations

Metal particles like aluminum and boron are of great interest as additives to energetic materials due to their high gravimetric and volumetric heat of combustion. However, the ignition temperatures of metals are quite high and their burning rates which depend upon the surface area of the burning metal agglomerates are quite slow. The naturally formed oxide layer on the surface of metal particles can further inhibit their ignition and combustion by limiting fuel/oxidizer transport. The boron oxide layer on boron particles is of particular interest due to the strong diffusion barrier formed by its presence. However, the ignition temperature ...


Calcium Passivation And Properties Of Al/Ca Composite Conductors, Charles Czahor Jan 2019

Calcium Passivation And Properties Of Al/Ca Composite Conductors, Charles Czahor

Graduate Theses and Dissertations

Light, strong, high-conductivity materials are desirable for overhead power transmission and distribution conductors. An aluminum/calcium composite with nanofilamentary reinforcement was produced by powder metallurgy and deformation processing to fine wires. Upon achieving the desired dimension, the wires were heat treated to convert the calcium to Al2Ca intermetallic reinforcement filaments. Extended heat treatments were used to evaluate the upper operating temperature of the material. The processing steps, microstructure, conductivity, and tensile strength of Al/Ca composites were evaluated. The measured properties indicate that the number of support towers required for a HVDC transmission line can be reduced by more than ...


Insights Into Performance Stability Of Lead-Free Piezoelectric Ceramics, Zhongming Fan Jan 2019

Insights Into Performance Stability Of Lead-Free Piezoelectric Ceramics, Zhongming Fan

Graduate Theses and Dissertations

Developing materials with superior functional properties is the primary goal of materials engineering. Nonetheless, the stability of performance during practical service should be of equal importance. This is, with no doubt, also true for piezoelectric materials.

The working conditions of piezoelectric materials can lead to either gradual or abrupt degradation in their functional properties. First, fatigue. In analogy to structural materials under cyclic stresses, the piezoelectric properties deteriorate during the electric field cycling. Second, aging. While the service is paused and the piezoelectric material is sitting idle, the piezoelectric properties will decay over time. Third, thermal depolarization. Electronic devices are ...


The Role Of Vec And Local Atomic Environment In Structural Transitions And Stability Of Complex Intermetallic Compounds Through Theoretical And Experimental Study Of Γ-Brasses, Stephanie L. Eveland Jan 2019

The Role Of Vec And Local Atomic Environment In Structural Transitions And Stability Of Complex Intermetallic Compounds Through Theoretical And Experimental Study Of Γ-Brasses, Stephanie L. Eveland

Graduate Theses and Dissertations

The fusion of computational and synthetic techniques provides a powerful investigative arsenal for a systematic consideration of the factors governing the structural makeup and observed physical properties of complex intermetallic compounds such as the non-uniform mixed sites in Mn2+xZn11-x, VEC driven structural transition in Mn5-yAl8-xZnx+y, and atypical atomic decoration of Cu9Al4 γ-brasses. Classic solid state synthetic techniques, self-flux techniques, as well as multiple structural characterization methods such as X-ray diffraction and electron microscopy were employed in the experimental portion of this work. Magnetic susceptibility measurements were utilized when appropriate in the study of the γ- brasses of Mn2 ...


Oleds: Light Extraction And Deep Blue Emission, Chamika Manoj Dulanja Hippola Jan 2019

Oleds: Light Extraction And Deep Blue Emission, Chamika Manoj Dulanja Hippola

Graduate Theses and Dissertations

OLEDs have emerged in the market over the last decade mainly in display applications due to their unique and attractive properties, such as lightweight, high brightness with strong color contrast, thin and flexible designs as well as potentially of low cost. OLEDs for lighting applications are under extensive research and development. Though promising for solid-state lighting, there are critical aspects that need to be addressed to increase their efficiency, which will lead to commercialization.

One major issue is the ~20% OLEDs’ limited forward outcoupling efficiency. This is due to several loss processes. More specifically, light generated in the emissive layer ...


Determination Of The Structure-Processing-Properties Relationship Of Fe-6.5wt%Si, Chad Richard Macziewski Jan 2019

Determination Of The Structure-Processing-Properties Relationship Of Fe-6.5wt%Si, Chad Richard Macziewski

Graduate Theses and Dissertations

The role of Fe-6.5wt%Si as a soft magnetic material in motor and power generation will continue to increase as power and efficiency demands keep increasing due to high silicon steel’s superior magnetic and electrical properties when operated at high frequencies. However, the presence of brittle phases creates challenges for mass production of the materials and for machining the materials into parts with demanding geometries. Understanding the processing parameters controlling the presence of the brittle phases is necessary to promote high silicon steels as the superior soft magnetic material. This research pioneers the use of in-situ cooling rate ...


An Investigation Of An Ionic Liquid Analog To The Conventional Metal-Oxide-Semiconductor Field-Effect Transistor, Richard Effler Jan 2019

An Investigation Of An Ionic Liquid Analog To The Conventional Metal-Oxide-Semiconductor Field-Effect Transistor, Richard Effler

Graduate Theses and Dissertations

An ionic circuit analogous to a traditional metal-oxide semiconductor was investigated, using 1-ethyl-3-methylimidazolium trifluoromethanesulfonate as the ionic liquid in the gating element. The circuit was observed to perform with comparatively high threshold and overdrive voltages in a region below the saturation current of the transistor. The concept of the design was successfully verified, although further improvements in electrode positioning and manufacturing precision are warranted.


Towards Understanding Material Characteristics Through The Additive Manufacturing Arc, Alden Watts Jan 2019

Towards Understanding Material Characteristics Through The Additive Manufacturing Arc, Alden Watts

Graduate Theses and Dissertations

The directed energy powder feed additive manufacturing (AM) process fabricates components with good quality, accuracy, and efficiency. However, this is a complex process and without careful consideration can lead to discontinuities in the final product such as porosity, cracks, or unfavorable microstructure. These material discontinuities may occur due to the limited understanding of the relationship between AM source materials and the evolution of the composition and microstructure during the deposition process. This makes it vital to study and correlate the composition, morphology, and characteristics of both the source material and of the final printed parts. In this research the properties ...


Gelation Mechanism, Synthesis, Characterization, And Applications Of Bio-Based And Model Thermoplastic Elastomers Via Raft Polymerization, Fang-Yi Lin Jan 2019

Gelation Mechanism, Synthesis, Characterization, And Applications Of Bio-Based And Model Thermoplastic Elastomers Via Raft Polymerization, Fang-Yi Lin

Graduate Theses and Dissertations

This dissertation report focuses on block copolymers derived from biomass along with a model methacrylate system to study the gelation behavior during reversible addition-fragmentation chain transfer (RAFT) polymerization due to the multi-functionality of bio-derived monomers. There are two bio-based block copolymer systems disclosed in this report. One is poly(styrene-blockacrylated epoxidized soybean oil) (PS-PAESO) derived from soybean oil. Thanks to the architecture of triglycerides, PS-PAESO block copolymers are found to resemble star block copolymers at low degree of polymerization (DP) and bottlebrush block copolymers at high DP. The long aliphatic chains of AESO act as the star arms in the ...


Structure Prediction Of Self-Assembled Nanoparticle Superlattices, Nathan Robert Horst Jan 2019

Structure Prediction Of Self-Assembled Nanoparticle Superlattices, Nathan Robert Horst

Graduate Theses and Dissertations

In this dissertation, the self-assembly of nanoparticle superlattices is studied through the development of theoretical models and computational techniques that elucidate the interactions of constituents during the self-assembly process. Specifically, configurational characteristics of various core-shell nanoparticle morphologies are explored with models of increasing complexity, aided by the implementation of molecular dynamics simulations and dynamic lattice theory.


Solution Phase Synthesis Of Lead-Free Perovskite And Perovskite-Inspired Materials, Rainie Dean Nelson Jan 2019

Solution Phase Synthesis Of Lead-Free Perovskite And Perovskite-Inspired Materials, Rainie Dean Nelson

Graduate Theses and Dissertations

This dissertation is a broad overview of research in the field of lead-free perovskite

inspired materials. While lead halide perovskites have promising properties, we sought to

investigate non-toxic alternatives – typically ones containing bismuth halides. We looked

into the flexibility of this element to be produced on different length scales, fabricating films

from bulk material, synthesizing nanocrystals, and growing crystals of 2D layered double

perovskites. We discovered that due to complexation with a solvent, bismuth iodide films can

be morphology controlled through use of solvent additives. During our synthesis of Cs3Bi2X9

nanocrystals, we found that BiX3 precursors possessed photoluminescence and that ...


Two-Dimensional Early Transition Metal Carbides As Supports For Platinum Catalysts, Zhe Li Jan 2019

Two-Dimensional Early Transition Metal Carbides As Supports For Platinum Catalysts, Zhe Li

Graduate Theses and Dissertations

Tuning catalytic active sites through metal-support interactions (MSIs) has emerged as an effective strategy to design supported metal catalysts. The development and selection of supports are paramount for achieving the desired catalytic performance, which are however, great challenges. This dissertation involves elucidating the MSIs between platinum and two-dimensional early transition metal carbides (MXenes) and harnessing the MSIs for several industrial catalytic processes and electrocatalytic reactions.

This work discovered the reactive metal support interactions (RMSI) in MXenes supported Pt catalysts. RMSI refers to a chemical reaction between a metal and the support that induces the formation of bimetallic structures. By utilizing ...


Deep Learning For Human Engineered Systems: Weak Supervision, Interpretability And Knowledge Embedding, Sambuddha Ghosal Jan 2019

Deep Learning For Human Engineered Systems: Weak Supervision, Interpretability And Knowledge Embedding, Sambuddha Ghosal

Graduate Theses and Dissertations

Pattern recognition has its origins in engineering while machine learning developed from computer science. Today, artificial intelligence (AI) is a booming field with many practical applications and active research topics that deals with both pattern recognition and machine learning. We now use software and applications to automate routine labor, understand speech (using Natural Language Processing) or images (extracting hierarchical features and patterns for object detection and pattern recognition), make diagnoses in medicine, even intricate surgical procedures and support basic scientific research.

This thesis deals with exploring the application of a specific branch of AI, or a specific tool, Deep Learning ...


Design And Development Of Cellulose Based Composites For The Built Environment, Melvin Glenn Veigas Jan 2019

Design And Development Of Cellulose Based Composites For The Built Environment, Melvin Glenn Veigas

Graduate Theses and Dissertations

Cellulose is a versatile material with numerous contemporary applications in textiles, food, and biomaterials. Contemporary research is focused on modifying the structural and thermal properties of cellulose to create novel composites with cellulose nano-crystals, lignocellulosic pulp, and foamed cellulose to name a few. Significant advances have been made in improving the properties of cellulose. Adding aligned cellulose nano-fibers to concrete to improve its mechanical properties or combining with polymers for better durability can lead to new applications specifically in design and construction. These new forms of cellulose through optimization and combination with other materials provide opportunities for reducing material usage ...


Use Of Cellular Automata-Based Methods For Understanding Material-Process-Microstructure Relations In Alloy-Based Additive Processes, Matthew Rolchigo Jan 2018

Use Of Cellular Automata-Based Methods For Understanding Material-Process-Microstructure Relations In Alloy-Based Additive Processes, Matthew Rolchigo

Graduate Theses and Dissertations

Deposition of metals through additive manufacturing has garnered research interest as of late due to the large range of potential industry applications. In particular, direct metal deposition processes such as Laser Engineered Net Shaping (LENS) have the ability to construct near net shape parts, open cellular structures, compositionally graded parts, and parts with improved mechanical properties over those manufactured via traditional methods such as casting and forging. To utilize additive processes to their full potential, it is imperative that the relationships among process parameters, development of the molten pool, microstructure, and properties are understood. Our goal in applying computational modeling ...


Exploration Of Alnico Permanent Magnet Microstructure And Processing For Near Final Shape Magnets With Solid-State Grain Alignment For Improved Properties, Aaron Gregory Kassen Jan 2018

Exploration Of Alnico Permanent Magnet Microstructure And Processing For Near Final Shape Magnets With Solid-State Grain Alignment For Improved Properties, Aaron Gregory Kassen

Graduate Theses and Dissertations

Economic uncertainty in the rare earth (RE) permanent magnet (PM) marketplace as well as a quickly evolving electric drive motor market which has decided to leverage permanent magnet synchronous AC drive (PMAC) motors as the motor of choice, has driven renewed research in RE-free permanent magnets such as “alnico.” Alnico, essentially an Al-Ni-Co-Fe magnet alloy, was displaced for high energy density applications by RE-containing magnets in the 1970’s due to their high-energy performance and high coercivities.

The current PMAC development trajectory requires the development of a sustainable magnet material choice, which not only has impressive mechanical properties, such as ...


Effect Of Nanoparticle Additives On The Tribological Behavior Of Oil Under Boundary Lubrication, Yosef Jazaa Jan 2018

Effect Of Nanoparticle Additives On The Tribological Behavior Of Oil Under Boundary Lubrication, Yosef Jazaa

Graduate Theses and Dissertations

In this study, three different nanoparticles (CuO, WC, WS2) of comparable nominal diameter, were added to a Polyalphaolefin (PAO) base oil to evaluate tribological response in the boundary lubrication regime. The concentration of particles was fixed at 1% by weight for this study and different surfactants (Oleic acid, polyisobutylene succinimide) and dispersion methods were employed to determine the impact on agglomeration and the observed tribological response. The results showed that of the methods studied, adding 10 % Oleic acid (OA) while sonicating the particles for 30 minutes reduced the agglomeration the most and adding 1% Oleic acid while sonicating the particles ...


Solution Phase Synthesis And Computational Investigation Of Pnictide Based Nowotny-Juza Phases, Miles Arthur Burris White Jan 2018

Solution Phase Synthesis And Computational Investigation Of Pnictide Based Nowotny-Juza Phases, Miles Arthur Burris White

Graduate Theses and Dissertations

Filled tetrahedral semiconductors comprised of elements from group I, II, and V of the periodic table are of interest to the thermoelectric, photovoltaic, and battery fields due to their tunable electronic structures. However, until recently, the synthesis of these materials in a facile and scalable manner had remained elusive. In this thesis, we demonstrate the solution phase synthesis of three members of this class of compounds (LiZnP, LiCdP, and LiZnSb). Furthermore, we explore the presence of polytypism in these compounds and computationally investigate which additional phases would be expected to display polytypism. Finally, we closely investigate the phase space of ...


Characterization Of Lithium Thiosilicophosphate Glasses Prepared By High Energy Ball Milling, Mark Anthony Paul Aguilar Jan 2018

Characterization Of Lithium Thiosilicophosphate Glasses Prepared By High Energy Ball Milling, Mark Anthony Paul Aguilar

Graduate Theses and Dissertations

An increasing demand for renewable energy has catalyzed investigations into improving battery technology. High energy density, longer cycling life, and safer battery materials are highly desirable. Research must go into developing advanced battery materials with properties designed for fast ionic conductivity, good chemical stability with the anode, and facile and low cost formability. Studying the short-range and intermediate-range atomic structures of materials will give insight into relationships between the atomic level structures of battery materials and their properties. In this research, the focus was upon developing new lithium ion conducting amorphous solid electrolytes in the compositional series 0.6 Li2S ...


Liquid-Phase Diffusion Bonding And The Development Of A Cu-Ni/Sn Composite Solder Paste For High Temperature Lead-Free Electrical Connections, Stephanie Michele Choquette Jan 2018

Liquid-Phase Diffusion Bonding And The Development Of A Cu-Ni/Sn Composite Solder Paste For High Temperature Lead-Free Electrical Connections, Stephanie Michele Choquette

Graduate Theses and Dissertations

After gathering sufficient microstructural evidence that a practical high-temperature lead-free solder could be produced through liquid-phase diffusion bonding (LPDB) of gas-atomized Cu-Ni powder blended with SN100C (Sn-0.7Cu-0.05Ni, wt.%) commercial solder powder, additional research was completed to enable design of a prototype composite solder paste. By reviewing several experimental alternatives to LPDB for use as replacements and improvements to the currently-used high-Pb solders (which will inevitably be banned by the EU’s RoHS directive), the choice to pursue the prototype solder paste research was verified. One key difference between this research and that of others is the method of ...


Environments-By-Design: Developing New Tools To Bring “Field Conditions” To The Laboratory, Kara Lind Jan 2018

Environments-By-Design: Developing New Tools To Bring “Field Conditions” To The Laboratory, Kara Lind

Graduate Theses and Dissertations

Maximizing agricultural yields is an urgent priority for our society as the world population will increase to 9 billion by 2050. Additionally, climate change could have detrimental effects on food supply and biomass production. Addressing these problems means considering the relationship the environment has on a plant’s development. The reality is though that there are few tools to plant scientists that can properly control and monitor the growing environment for plant. We believe that as engineers we can provide plant scientists with new tools which we call “environments by design”. These tools can control the environmental stimuli either abiotic ...


Fracture And Deformation Of Soft Materials And Structures, Zhuo Ma Jan 2018

Fracture And Deformation Of Soft Materials And Structures, Zhuo Ma

Graduate Theses and Dissertations

Soft materials and structures are very common in our daily life and industry products, but still shows great potential on many innovative applications. To make better use of them, we need a good understanding of the fracture and deformation of the materials. Starting from soft elastic foams, this paper proposes a scaling law for the fracture energy of soft elastic foam by using the analogy between the cellular structure and the network structure of rubbery polymers. To verify the scaling law, a phase-field model for the fracture processes in soft elastic structures is developed. The numerical simulations in two-dimensional foam ...


Interfacial Degradation Mechanisms With Applications To Polymer-Matrix Composites And Intergranular Stress Corrosion Cracking Of Steels, Denizhan Yavas Jan 2018

Interfacial Degradation Mechanisms With Applications To Polymer-Matrix Composites And Intergranular Stress Corrosion Cracking Of Steels, Denizhan Yavas

Graduate Theses and Dissertations

Structural interface property controls a wide spectrum of applications, ranging from the hybrid integration of dissimilar structural materials, to the enhanced physical properties of high performance engineering alloys. Practically, interfaces can be perceived as the weakest part of a heterogonous material or a structure. They are the most prone to environmental disturbances such as chemical or thermal, with significant deterioration of the structural integrity. Despite the large volume of literature on the topic, there remains a lack of proper understanding of degradation mechanisms of these interfaces. The challenge remains in the early detection of interfacial damage, and assessment of the ...


Gellan Gum Based Thiol-Ene Hydrogels With Tunable Properties For Use As Tissue Engineering Scaffolds, Zihao Xu Jan 2018

Gellan Gum Based Thiol-Ene Hydrogels With Tunable Properties For Use As Tissue Engineering Scaffolds, Zihao Xu

Graduate Theses and Dissertations

Gellan gum is a naturally occurring polymer that can crosslink in the presence of divalent cations to form biocompatible hydrogels. However, physically crosslinked gellan gum hydrogels lose stability under physiological conditions, which substantially limits the applications of these hydrogels in vivo. In order to improve the mechanical strength, we incorporated methacrylate into gellan gum and chemically crosslinked the hydrogel through three polymerization methods: step growth through thiol-ene photoclick chemistry, chain growth via photopolymerization, and mixed model in which both mechanisms were employed. Methacrylation was confirmed and quantified by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR ...


A Framework For Isogeometric-Analysis-Based Design And Optimization Of Wind Turbine Blades, Austin Herrema Jan 2018

A Framework For Isogeometric-Analysis-Based Design And Optimization Of Wind Turbine Blades, Austin Herrema

Graduate Theses and Dissertations

Typical wind turbine blade design procedures employ reduced-order models almost exclusively for early-stage design; high-fidelity, finite-element-based procedures are reserved for later design stages because they entail complex workflows, large volumes of data, and significant computational expense. Yet, high-fidelity structural analyses often provide design-governing feedback such as buckling load factors. Mitigation of the issues of workflow complexity, data volume, and computational expense would allow designers to utilize high-fidelity structural analysis feedback earlier, more easily, and more often in the design process. Thus, this work presents a blade analysis framework which employs isogeometric analysis (IGA), a simulation method that overcomes many of ...


An Integrated Model For The Probabilistic Prediction Of Yield Strength In Electron-Beam Additively Manufactured Ti-6al-4v, Thomas Kiel Ales Jan 2018

An Integrated Model For The Probabilistic Prediction Of Yield Strength In Electron-Beam Additively Manufactured Ti-6al-4v, Thomas Kiel Ales

Graduate Theses and Dissertations

A complete model for the prediction of the yield strength of Titanium 6Al-4V in an additively manufactured component is presented herein. A thermal model is presented utilizing the ABAQUS simulation software to provide the process leg of the materials tetrahedron. The thermal model is fed into an implementation of the Langmuir equation that has been adapted for use in the simulation of the Electron-Beam Additive Manufacturing (EBAM) process. The predicted chemistry provided by the Langmuir equation for the Ti-6Al-4V alloy is then used in a phenomenological equation for the prediction of yield strength; a design probability curve is generated through ...


Simple Solutions To The Fabrication Of Textured And Porous Coatings, Xinchun Tian Jan 2018

Simple Solutions To The Fabrication Of Textured And Porous Coatings, Xinchun Tian

Graduate Theses and Dissertations

Functional coatings can change the surface properties of the substrate, add entirely new surface functionalities, or preserve the substrate. They provide solutions to many key engineering problems where different functionalities between the surface and the bulk are required. Among them, textured coatings are characterized by their surface roughness, film porosity, and surface chemistry. They are useful for applications ranging from superhydrophobic surfaces to artificial implants to thermal barrier coatings. However, the use and deployment of new coating methods are hampered in real applications due to the lack of a comprehensive consideration of the associated issues. In this thesis, two deposition ...


Numerical Analysis Of A Non-Polymeric Double-Network Composite, Qitong Yao Jan 2018

Numerical Analysis Of A Non-Polymeric Double-Network Composite, Qitong Yao

Graduate Theses and Dissertations

Double-network hydrogels have drawn much attention for its combined mechanical properties of high stretchability and high mechanical strength and numerous studies have been conducted on these hydrogels with specific emphasis on gel compositions and mechanisms. Additionally, there are also reports on application of double-network gel mechanisms on macro composites which achieved similar results as in the gels. In this thesis, a series of numerical simulations on designing and tuning of a double-network hydrogel inspired non-polymeric composite formed with a coiled serpentine network acting as the long-chain and a solid plate acting as the short-chain are presented. The simulation results show ...


Precision Radio-Frequency And Microwave Dielectric Spectroscopy And Characterization Of Ionic Aqueous Solutions, Amin Gorji-Bandpy Jan 2018

Precision Radio-Frequency And Microwave Dielectric Spectroscopy And Characterization Of Ionic Aqueous Solutions, Amin Gorji-Bandpy

Graduate Theses and Dissertations

Excessive amounts of chemicals and ions flowing into water sources, which are mainly due to efflux from agricultural lands, cause serious environmental and human-health related concerns. The lack of affordable and real-time monitoring systems for these contaminants limits effective conservation and management strategies. To establish a basis for developing an effective, fast, real-time, and affordable sensing system, dielectric spectroscopy has been applied to characterize agriculturally-relevant aqueous solutions of most commonly found ions in tile drainage water. Dielectric spectra of aqueous sodium chloride (NaCl), sodium nitrate (NaNO3), and sodium sulphate (Na2SO4) ionic solutions, which are the common pollutants found in agricultural ...


Design And Performance Assessment Of Chip Seal Applications, Minas Guirguis Jan 2018

Design And Performance Assessment Of Chip Seal Applications, Minas Guirguis

Graduate Theses and Dissertations

The research evaluates the effectiveness of chip seal treatments when rational design, good materials, good construction and good agency oversight work together. The work investigates the effectiveness of chip seal applications using short-term and long-term quantitative test results from various chip seal roadways located in Oregon. Laboratory testing is utilized to understand and reflect the importance of aggregate characterization to ensure the success of performance. Findings show that chip seal preserved Oregon’s roadways by improving their surface texture properties and protecting them from additional cracking and deterioration.

The study further evaluates the effect of various parameters on chip seal ...