Engineering Commons^™

Thermomechanical Process Simulation And Quantification Of Nanoscale Precipitation Influencing Ductility And Strength During Alloy Processing, Alyssa Stubbers

Theses and Dissertations--Chemical and Materials Engineering

Experimental process simulation and quantification of microstructure development during processing are challenging due to limitations with machinery temperature capability, inadequate resolution and sampling volume of currently available characterization techniques, and difficulty characterizing material microstructures as close to processing-relevant conditions as possible. This dissertation addresses how process simulation can be performed using Gleeble thermomechanical technologies and how microstructure development during these processing simulations can be quantified both in-situ and ex-situ.

The first portion of this dissertation demonstrates how Gleeble technologies can be applied to simulate complex material processing conditions in order to produce process-property profiles that can be used to inform …

Interfacial Thermomechanical Behavior Of Hybrid Carbon Fibers, Sriraj Srihari

Doctoral Dissertations and Master's Theses

The carbon fiber/epoxy interface is of great importance in composite design due to its load transfer mechanisms from the weak epoxy to the stronger fiber. Improving the strength of the interface reduces the risk of failure at the interface and improves the load transfer to the fiber. In this study, two types of nano-species ZnO nanowires and nickel-based metal organic frameworks were grown on carbon fibers to improve the interfaces. The interfacial mechanics of the enhanced fibers are evaluated using nanoindentation studies. Composite samples with Aeropoxy matrix and vertically aligned fibers are fabricated for this purpose. A Bruker TI-980 TriboIndenter …

Thermal, Magnetic, And Electrical Properties Of Thin Films And Nanostructures: From Magnetic Insulators To Organic Thermoelectrics, Michael J. M. Roos

Electronic Theses and Dissertations

Modern fabrication and growth techniques allow for the development of increasingly smaller and more complex solid state structures, the characterization of which require highly specialized measurement platforms. In this dissertation I present the development of techniques and instrumentation used in magnetic, thermal, and electrical property measurements of thin films and nanostructures. The understanding of trapped-flux induced artifacts in SQUID magnetometry of large paramagnetic substrates allows for the resolution of increasingly small moments. Using these methods, the antiferromagnetic coupling of the interface between a Y₃Fe₅O₁₂ film and Gd₃Ga₅O₁₂substrate is quantitatively …

A Study Of Biochar Production Via Continuous Vacuum-Assisted Pyrolysis, Max Wohlgenant

Graduate Theses & Non-Theses

The present study focuses upon the design, fabrication, and feasibility of the bulk production of scientific biochar for mobile delivery. In the 2022 annual report, the National Academies of Science, Engineering, and Medicine recommended the integration of mobile, decentralized reactors that employ flexible manufacturing and circular economic principles. Biochar production, involving the thermal degradation of biomass under an inert atmosphere to yield remediation media is an ideal material to satisfy this recommendation. Many potential application sites, such as abandoned mines, are remote and limit the construction of large infrastructure. The continuous vacuum-assisted pyrolysis (CVAP) reactor was designed to: increase biochar …

Characterization Of Hydrogen Embrittlement Sensitivity In High Hardness Steels, David Ahlen Salley

Theses and Dissertations

High hardness steels can be affected by delayed brittle cracking often attributed to hydrogen embrittlement. Improved resistance to hydrogen embrittlement would be beneficial to many industries including military, automotive, and high-rise construction. While other prevention methods include coating, trapping, and barriers, design efforts in this study were focused on improving intrinsic properties to be more resistant to hydrogen embrittlement. Four alloys targeting 477 – 534 HB were designed and produced in-house and compared against a commercial grade 500 HB alloy. Charpy V-notch (CVN) impact toughness and tensile specimens were made according to ASTM E23 and ASTM E8 to characterize mechanical …

Synthesis And Property Characterization Of Rare-Earth High-Entropy Oxides With Pyrochlore-Type Structures, Candice Kinsler-Fedon

Doctoral Dissertations

In the search for novel materials with advanced physical properties, the concept of adding configurational entropy onto a single atomic site is known to provide new avenues toward material discovery. In the case of high entropy oxides (HEOs), the ability to “tune” a material’s properties by having multiple cations on single or multiple sites allows for greater opportunity to design materials for specific applications. The work presented here explores the synthesis of new multicomponent (high entropy) oxides, followed by a detailed characterization using several techniques. We have successfully synthesized multiple single-phase polycrystalline rare-earth high entropy oxides and grown large, bulk …

Material Characterization Of Compression Molded Composites, Broderic Clement-Thorne

Electronic Thesis and Dissertation Repository

Composite materials are widely used in the automotive industry to keep cost and weight down. The ability to simulate the fabrication of parts is an important way to use resources effectively. The molding process can also have very dramatic effects on material properties. These properties are determined by the microstructure of the polymer composite material, including the length, concentration, and orientation of the fibers used as reinforcement. Therefore this study seeks to characterize the material properties of a long glass fiber reinforced polyamide composite, the effects of molding conditions on those material properties, and characterization of the microstructure of the …

Synthesis And Advanced Characterization Of Energy Materials, Erik Sarnello

Graduate Research Theses & Dissertations

Catalysts are used in an extremely broad range of systems including everything from biological systems to industrial processes. An ideal catalyst offers robust stability and high activity. This work focuses on the synthesis and characterization of materials that show promise in the field of catalysis. Advanced synchrotron characterization techniques and unique experimental design are highlighted to provide foundation work that will provide the necessary information to aid in designing and fabricating catalytic materials. Supported metal nanoparticle (SMN) catalysts are enormously crucial for many catalytic applications. However, catalyst deactivation, caused by sintering and coke formation, is a ubiquitous problem that significantly …

Corrosion Protection Mechanisms Of Trivalent Chromium Based Passivations On Γ-Znni Coated Al6061-T6 Alloy, Kevin Foster

Doctoral Dissertations

“The role of cobalt in trivalent chromium passivations (TCPs) to improve corrosion resistance of γ-ZnNi coated steel and aluminum is based on its effect on hexavalent chromium content in the passive layer. Investigations of both a cobalt-containing and cobalt-free TCP on SAE 1008 steel indicated that both passivations protect well for up to 1000 hours in neutral salt spray exposure (SSE). A repetition on Al 6061-T6 alloy indicated that TCP performed much better than cobalt-free TCP implicating the underlying substrate. Optical and electron micrographs indicated physical changes such as crack thickness, crack density, passivation porosity, and passivation thickness existed between …

Characterization Of Cermet Fuel For Nuclear Thermal Propulsion (Ntp), James Floyd Mudd

Masters Theses

“A manned flight to Mars is met with many technical challenges, not the least of which is the development of propulsion technology capable of moving a transit vehicle from Earth orbit to Mars orbit. NASA is investigating Nuclear Thermal Propulsion (NTP) as a way of reducing flight time and providing the option for a mid-mission abort. NTP, which uses a high temperature nuclear reactor to heat a propellant, requires advanced fuel materials capable of withstanding temperatures well in excess of 2000 K. Among the fuel options are ceramic metal (cermet) composites composed of refractory metals and Ultra-High Temperature Ceramics (UHTCs). …

Radiation Effects On Lithium Indium Diselenide Semiconductors As Neutron Imaging Detectors, Robert M. Golduber

Masters Theses

The studies presented in this work aim to improve upon the knowledge base of lithium indium diselenide (LISe) semiconductors to understand how the material behaves in high radiation environments and refine the process of turning it into a neutron detector. LISe has great potential as neutron imaging detector because of the high neutron absorption efficiency of its enriched ⁶Li component and its ability to discriminate between gamma-rays and neutrons. Its ability to remain functional after being irradiated with large amounts of neutron fluence has been tested and the change in its electro-optical properties with relation to fluence has been …

Defect Evolution In High-Temperature Irradiated Nuclear Graphite, Steve Johns

Boise State University Theses and Dissertations

Graphite has historically been used as a moderator material in nuclear reactor designs dating back to the first man-made nuclear reactor to achieve criticality (Chicago Pile 1) in 1942. Additionally, graphite is a candidate material for use in the future envisioned next-generation nuclear reactors (Gen IV); specifically, the molten-salt-cooled (MSR) and very-high-temperature reactor (VHTR) concepts. Gen IV reactor concepts will introduce material challenges as temperature regimes and reactor lifetimes are anticipated to far exceed those of earlier reactors. Irradiation-induced defect evolution is a fundamental response in nuclear graphite subjected to irradiation. These defects directly influence the many property changes of …

Nanoscale Optical And Correlative Microscopies For Quantitative Characterization Of Dna Nanostructures, Christopher Michael Green

Boise State University Theses and Dissertations

Methods to engineer nanomaterials and devices with uniquely tailored properties are highly sought after in fields such as manufacturing, medicine, energy, and the environment. The macromolecule deoxyribonucleic acid (DNA) enables programmable self-assembly of nanostructures with near arbitrary shape and size and with unprecedented precision and accuracy. Additionally, DNA can be chemically modified to attach molecules and nanoparticles, providing a means to organize active materials into devices with unique or enhanced properties. One particularly powerful form of DNA-based self-assembly, DNA origami, provides robust structures with the potential for nanometer-scale resolution of addressable sites. DNA origami are assembled from one large DNA …

Characterization Of The Surface Condition In Aa6061 Resulting From Deep Rolling As A Function Of Common Industrial Parameters, Andrew Kenneth Layer

Masters Theses

"Roller burnishing is widely used in industry to improve the surface finish and fatigue life of components. As weight reduction continues to grow in the automotive and transportation industries, deep rolling can help maintain product performance by mitigating the increase in component stresses resulting from lower weight systems. Deep rolling parameters such as tool, applied angle, feed rate, spindle speeds, and relative tool direction all affect cycle time, product performance, and appearance. The effects of common industrial parameters on the resultant surface roughness and residual stress profiles were studied in this investigation. The samples were manufactured on a CNC lathe …

Combinatorial Screening Approach In Developing Non-Equiatomic High Entropy Alloys, Azin Akbari

Theses and Dissertations--Chemical and Materials Engineering

High entropy alloys (HEA) are a relatively new group of alloys first introduced in 2004. They usually contain 5 to 6 different principle elements. Each of these elements comprise 5-35 at. % of the chemical composition of the alloy. There is a growing interest in the research community about the development of these alloys as well as their engineering applications. Some HEAs have interesting properties that have made them well suited for higher temperature applications, particularly refractory uses, while some have been shown to maintain their mechanical properties even at cryogenic temperatures.

Initially, the HEA research was focused on developing …

Characterization And Modeling Of Asphalt Concrete For Dynamic Properties And Performances, A S M A. Rahman

Civil Engineering ETDs

The recently developed mechanistic-empirical pavement design guide (MEPDG, also known as Pavement M-E design method) uses the nationally calibrated, binder viscosity-based dynamic modulus predictive model for the design and analysis of asphalt pavements. In this study, this model is assessed for its appropriateness for asphalt-aggregate mixtures typically used in New Mexico. In essence, this study investigates the predictability issue of complex modulus of New Mexico mixes. A total of 54 Superpave mixes with different aggregate gradations, air voids, and binder grades were collected from the mixing plants and from the pavement construction sites. The loose asphalt mixtures were then compacted, …

High Temperature Oxidation And Metal Dusting Resistance Of Traditional Iron-Based And Novel Alumina Forming Austenitic Alloys, Wen-Chieh Lee

Theses and Dissertations

Metal dusting is a catastrophic form of corrosion and carburization, and is a disintegration of alloys into a dust of metal particles, oxides and graphite deposition products. Metal dusting and related coking phenomenon happen in industrial fields where carburizing syngas appears in the process. Metal dusting would cause damage in the form of pits and notches in pipes and other metallic equipment often causing a loss of production time or reduced component lifetimes. It is of great importance to prevent this corrosion from happening to the metal materials used by the industry.

To counter the corrosion, a new generation of …

Processing-Property-Structure Relationships Of Carbonaceous Materials Derived From Renewable Lignin Products, Valerie García-Negrón

Masters Theses

Efforts to effectively use lignin, a by-product of paper and biofuels production, have been carried out for several decades. This renewable resource has potential for use as a carbonaceous material due to its aromatic structure and high carbon content, reminiscent of graphite. The search for new carbon-based materials is extremely active, because they are necessary components in many applications, such as energy storage, electronics, catalysis, and lubricants. Traditional carbon-based materials are derived or mined from petroleum or coal, thus, contributing to pollution, national security risks, and anthropogenic climate change. Lignin, a carbon-rich component found in the tissues of vascular plants, …

Fundamental Understanding Of Bond Formation During Solid State Welding Of Dissimilar Metals, Niyanth S

Doctoral Dissertations

Dissimilar metal welds are used in a wide range of applications to effect light weighting and for corrosion resistance. While fusion welding techniques are limited in their ability to fabricate dissimilar metal welds, solid state welding techniques are limited in their ability to fabricate complex geometries with dissimilar metal combinations. Hence alternative techniques need to be explored to fabricate complex geometries with dissimilar metals welds in the solid state. Ultrasonic additive manufacturing in a solid state additive manufacturing process that combines ultrasonic welding with mechanized tape layering to fabricate dissimilar metal welds in the solid state. Though extensive feasibility studies …

Characterization In 2d Sulfides And Graphene Composites For Sensing Applications, Alberto Delgado

Open Access Theses & Dissertations

In this work, we have evaluated 2D layered material composites for opto-electro-mechanical sensing applications. In particular, we have focused on TMDCs and graphite and studied the effects of chemical liquid exfoliation on the structural characteristics of the 2D layered materials, through particle size, x-ray diffraction, Raman and surface area analysis. An approach was developed to combine the solution-processed dispersion with organic and inorganic matrix materials for forming the composites. From Raman Spectroscopy of the ultra-sonicated samples, the I2D/IG>2 for graphite, and for MoS2 the difference between the A1g and E2g peak was 22.85cm-1, consistent with few layer 2D MoS2. …

Synthesis, Characterization, And Electrochemical Properties Of Polyaniline Thin Films, Soukaina Rami

USF Tampa Graduate Theses and Dissertations

Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of …

Seeing Red: Characterizing Historic Bricks At Sylvester Manor, Long Island, Ny 1652-1735, Martin John Schmidheiny

Graduate Masters Theses

The goal of this project is to develop a basic material characterization of the bricks excavated at the site of Sylvester Manor on Shelter Island, New York. In the early Manor period of 1650-1690, this early Northern provisioning plantation supplied Barbadian sugar operations and pursued mercantile interests independent of state control. Accounting for the range of production defects and material characteristics of the bricks suggests on-site or local manufacture as a regional ceramic industry developed. Qualitative visual analysis and petrographic thin-sections were used to characterize the internal composition, variation and production evidence in the bricks. Interpreting the results of this …

Growth And Analysis Of Micro And Nano Cdte Arrays For Solar Cell Applications, Brandon Adrian Aguirre

Open Access Theses & Dissertations

CdTe is an excellent material for infrared detectors and photovoltaic applications. The efficiency of CdTe/CdS solar cells has increased very rapidly in the last 3 years to ~20% but is still below the maximum theoretical value of 30%. Although the short-circuit current density is close to its maximum of 30 mA/cm2, the open circuit voltage has potential to be increased further to over 1 Volt. The main limitation that prevents further increase in the open-circuit voltage and therefore efficiency is the high defect density in the CdTe absorber layer. Reducing the defect density will increase the open-circuit voltage above 1 …

Dc, Rf, And Thermal Characterization Of High Electric Field Induced Degradation Mechanisms In Gan-On-Si High Electron Mobility Transistors, Matthew Anthony Bloom

Master's Theses

Gallium Nitride (GaN) high electron mobility transistors (HEMTs) are becoming increasingly popular in power amplifier systems as an alternative to bulkier vacuum tube technologies. GaN offers advantages over other III-V semiconductor heterostructures such as a large bandgap energy, a low dielectric constant, and a high critical breakdown field. The aforementioned qualities make GaN a prime candidate for high-power and radiation-hardened applications using a smaller form-factor. Several different types of semiconductor substrates have been considered for their thermal properties and cost-effectiveness, and Silicon (Si) has been of increasing interest due to a balance between both factors.

In this thesis, the DC, …

Material Characterization And The Effects Of Moisture And Drying On Injection Molded Torlon 5030, Michael R. Di Re

Master's Theses

The effects of water absorption and drying were studied on injection molded Torlon 5030, a high performance thermoplastic fabricated by Solvay Specialty Polymers. Torlon 5030 contains 30% by weight glass fibers in a polyamide-imide base resin. The objective behind this work was to test and better define relevant properties for industrial applications using this material. While the material design guide offers information on many mechanical properties including tensile, fatigue, and creep data; there is little to no publicly published data on the effects of water absorption and any subsequent drying of Torlon 5030. Blistering was also studied. With exposure to …

Characterization And Restoration Of Historic Rosendale Cement Mortars For The Purpose Of Restoration, Stephanie Hart

All Theses

Mortar was a very common building material in today's historic sites. Before Portland cement was manufactured at a global level, Rosendale cement was commonly used in these mortars. Over time, these mortars in historic sites have begun to break down and wear away. With Rosendale cement in production again, measures can be taken to restore and repair the historic mortars. However, little testing has been done to establish durability of modern Rosendale cement mortars. This presentation highlights the common mix techniques used at the time, and undergoes experiments to establish general properties and predict future durability. Six different mortar mixes …

The Characterization And Comparison Of Biochar Produced From A Decentralized Reactor Using Forced Air And Natural Draft Pyrolysis, Leah Herbert, Ian Hosek, Rishi Kripalani

Materials Engineering

The soil additive properties of biochar have proven both effective and globally beneficial, but depend heavily on feedstock used and process conditions. This study characterizes how forced and natural draft air flows affect the biochar’s soil amendment potential. Biochars manufactured from two pine species of feedstock, in timber and pellet form, were compared against a designer biochar. The designer biochar held the lowest C:N ratio (57.43), followed by the natural draft pellets (199.5), forced air timber (282.5), forced air pellets (422.7), and natural draft timber (503.7). The designer char had the largest cation exchange capacity at 138.5 cmolc/kg; the decentralized …

Deposition, Characterization, And Fabrication Of A Zinc Oxide Piezoelectric Thin Film Microspeaker Using Dc Reactive Sputtering, Adam Olzick

Master's Theses

A piezoelectric microspeaker device that could be used in a variety of acoustic applications was designed and fabricated using a thin film ZnO layer that was reactively DC sputtered onto a single crystalline n-type silicon substrate. When tested the microspeaker did not produce sound due to complications in the etching process, the thickness of the diaphragms, and clamping effects. Instead, a characterization approach was taken and the structural, optical, electrical, and piezoelectric properties of the ZnO were investigated. Scanning electron microscopy, x-ray diffraction, and atomic force microscopy were utilized to discover the ZnO’s structural properties. Using the XRD and SEM, …

Characterization And Optimization Of Solution-Derived Chalcogenide Glass Thin Films, Jacklyn Wilkinson

All Theses

Chalcogenide glasses have many unique properties that allow them to be used in a variety of optical applications. Infrared transparency allows them to be used in sensors for molecules that have 'fingerprints' in the 2-25 μm range. By producing amorphous thin films of these materials, they can be incorporated into chemical sensors as planar waveguides and resonators. The goal of this work was to fabricate and characterize solution-derived chalcogenide thin films for use in chemical sensors with a source wavelength between 3-3.5 μm.
The structural and optical properties of the parent bulk glass were characterized and used as reference for …

Nanoprobe I-V Characterization Of Cdte/Cds Micro And Nano-Patterned Solar Cells, Heber Prieto

Open Access Theses & Dissertations

This thesis presents a novel way to characterize micro and nano patterned cadmium telluride thin film solar cells via a nano-probe system. A historical review of CdTe-based solar cells is presented first followed by review of the technology developed to produce the patterned CdTe cells. A detailed presentation is then provided on the use of a Zyvex nanoprobing system to characterize the patterned solar cells. The I-V response of micro- and nano-patterned solar cells stimulated under different e-beam conditions is presented and analyzed. Suggestions of how to improve the technique are provided. This work documents, for the first time, the …