Materials Science and Engineering Commons^™

Exsolved Nanoparticle Decorated Redox Stable Ceramic Anode Material With High Performance For Solid Oxide Fuel Cells, He Qi

Graduate Theses, Dissertations, and Problem Reports (ETD)

The solid oxide fuel cell (SOFC) is an efficient high-temperature device that can directly convert chemical energy to electrical energy. Because of its high efficiency and environmental friendliness, extensive investigations have been made worldwide in past decades. Though broadly used as the anode material for Solid-Oxide Fuel Cells, Ni-YSZ is limited in some practical applications by severe carbon deposition on Ni in hydrocarbon fuels and a significant volume change of Ni-NiO among redox cycling. In order to overcome these problems and achieve excellent performance in the redox environment, a Ni-free ceramic material La_0.5Sr_1.5Fe_1.5Mo_{0.5 …}

Form Stable Phase-Change Materials, Russell Dent, Marjan Kashfipour, Nitin Mehra, Jiahua Zhu

Williams Honors College, Honors Research Projects

This work investigates the use of two different polyols, xylitol (Xyl) and erythritol (Ery), in conjunction with boron nitride (BN) aerogels, for the purpose of creating thermally conductive composites. While the BN filler in Xyl composites achieved a high anisotropic thermal conductivity of up to 4.53 W/m-K at 18.2 weight percent filler loading, they do not exhibit good phase-change material qualities due to a low solidification enthalpy even at low cooling rates. Alternatively, the BN-Ery composites have shown promising results with a solidification enthalpy of 225.14 J/g and a melting enthalpy of 385.84 J/g at a heat rate of 5 …

Interlaminar Damage Detection In Composite Materials, Hariharan Rangarajan

Williams Honors College, Honors Research Projects

Using ceramic matrix composites (CMCs) for high-temperature applications in jet engines increases durability and reduces weight and cooling requirements resulting in improved efficiency and fuel savings. Understanding, detecting, and monitoring different types of damage is essential to achieve optimal performance of CMC components. The Direct Current Potential Drop (DCPD) method is a non-destructive technique of estimating damage in composite materials.

DCPD technique works by measuring nodal potential differences when current is flown through the material. Direct current spreading in different woven and laminate composites is modeled to follow a ladder resistor network in which the nodal voltages decrease exponentially as …

Carbon Deposition On Ni/Ysz Anode Sofc For Direct Methane Steam Reforming, Haiyang Li

Graduate Theses, Dissertations, and Problem Reports (ETD)

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices that produce electricity directly from oxidizing fuels. Compared to direct combustion of hydrogen to generate power, it has a big advantage in aspects from efficiency and safety when using hydrogen as the fuel of SOFCs. Hydrocarbon reforming is one of the conventional methods to convert natural gas into hydrogen. While considering the difficulty in storage and transportation of hydrogen, we can utilize the supporting materials on the anode side of SOFCs as catalyst to generate hydrogen via hydrocarbon reforming process and pour the hydrogen as fuel into the SOFC system. Ni/YSZ is …

Enhancing The Thermoelectric Performance Of Calcium Cobaltite Ca3co4o9 Through Single And Dual Elements Doping, Cesar Octavio Romo De La Cruz

Graduate Theses, Dissertations, and Problem Reports (ETD)

Worldwide energy consumption losses more than 60% of the energy after its conversion, most of these losses are in the form of waste heat. Therefore, it is a matter of utmost importance to harness waste heat and reutilize this energy source to improve the overall conversion efficiency. Thermoelectric (TE) technology is one of the rising alternatives to harvest the excessive amount of energy lost as waste heat for a better and sustainable energy future. TE materials can utilize waste heat to improve efficiency in the ever-increasing demand for energy by converting a temperature difference directly into electricity due to the …

Electroless Nickel Plating And Spark Plasma Sintering Of Nano Zro2 For Mechanical Property Enhancement, Kunlong Jia

McKelvey School of Engineering Graduate Student Theses & Dissertations

A new approach of combined electroless nickel plating (ENP) and spark plasma sintering (SPS) was used to determine the feasibility of fracture toughness improvement of ZrO2. Nano-grained yttria stabilized zirconia (YSZ) particles of 100nm average diameter were coated with about 1-5 nm of nickel coating by ENP. To reduce nano particle agglomeration throughout the ENP process; vigorous agitation with an ultrasonic horn was used. The coated powder was characterized using Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and Transmission electron microscopy (TEM) to study the microstructure and coating characteristics. The coating was identified to be predominantly nickel and of …

Polyhedral Oligomeric Silsesquioxane-Phosphate Glass Matrix Nanocomposites With Additional Chapter On Phosphate Glass-Poly(Ethylene Terephthalate) Matrix Composites, Kyoungtae Kim

Dissertations

Preparation and characterization of tin fluorophosphate glass (Pglass) matrix nanocomposites incorporating polyhedral oligomeric silsesquioxane (POSS) were investigated on the structural, thermal, morphological, mechanical, and rheological properties. Various processes including synthesis, extrusion and sintering processes were applied to prepare the nanocomposite samples. Another application of POSS with hydrophobic functional groups on the well-structured nanoscale silicate cage with three silanol groups was investigated to present the feasibility to use POSS molecule as a coating material on the surface of the hydrophilic inorganic glass. In addition, Poly(ethylene terephthalate) polymer matrix composites incorporating Pglass was studied to present the benefits of the Pglass with …

A Note Of Thanks To John Halloran, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Measuring Characteristic Shrinkage Variability Due To Metal Loading Effects In Low Temperature Co-Fired Ceramic Using Image Processing, John Ezekiel Zumbro

Graduate Theses and Dissertations

Low temperature co-fired ceramic (LTCC) has many benefits when it comes to electronic packaging due to the low dielectric loss, reliability in extreme environments, and high breakdown voltage. Though the ceramic has a lot of benefits it is not widely used due to the high cost and complexities associated with manufacturing. One of these issues with manufacturing is compensating for the shrinkage of the ceramic, this is accomplished by using an expansion factor, creating the “green” or manufactured design. This expansion factor is approximated through knowledge of the ceramic factors such as the metal loading, layers of ceramic tape, firing …

Phonon Signature Of Charge Inhomogeneity In High Temperature Superconductors Yba2cu3o6+X, Y. Petrov, T. Egami, R. J. Mcqueeney, Mohana Yethiraj, Herbert A. Mook

Materials Science and Engineering Faculty Research & Creative Works

Temperature and composition dependences of high-energy longitudinal optical (LO) phonons in YBa₂Cu₃O_6+x, studied by inelastic neutron scattering measurements, provide clear evidence for temperature dependent spatial inhomogeneity of doped charges. The measurements indicate that charge doping increases the volume fraction of the charged regions, while the local charge density remains unchanged. For the optimally doped sample the charge distribution changes sharply near the superconducting transition temperature, with stronger charge inhomogeneity below TC. The remarkable magnitude of the phonon response to charge suggests strong involvement of phonons in charge dynamics.

Fabricating Functionally Graded Materials By Ceramic On-Demand Extrusion With Dynamic Mixing, Wenbin Li, Austin J. Martin, Benjamin Kroehler, Alexander M. Henderson, Tieshu Huang, Jeremy Lee Watts, Greg Hilmas, Ming-Chuan Leu

Materials Science and Engineering Faculty Research & Creative Works

Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently developed for fabricating dense, functional ceramic components. Presented in this paper is a further development of this process focusing on fabrication of functionally graded materials (FGM). A dynamic mixing mechanism was developed for mixing constituent ceramic pastes, and an extrusion control scheme was developed for fabricating specimens with desired material compositions graded in real time. FGM specimens with compositions graded between Al₂O₃ and ZrO₂ were fabricated and ultimately densified by sintering to validate the effectiveness of the CODE process for FGM fabrication. Energy dispersive spectroscopy …

Recyclability Of 304l Stainless Steel In The Selective Laser Melting Process, Austin T. Sutton, Caitlin S. Kriewall, Ming-Chuan Leu, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During part fabrication by selective laser melting (SLM), a powder-bed fusion process in Additive Manufacturing (AM), a large amount of energy is input from the laser into the melt pool, causing generation of spatter and condensate, both of which have the potential to settle in the surrounding powder-bed compromising its reusability. In this study, 304L stainless steel powder is subjected to five reuses in the SLM process to assess its recyclability through characterization of both powder and mechanical properties. Powder was characterized morphologically by particle size distribution measurements, oxygen content with inert gas fusion analysis, and phase identification by X-ray …

Tool For Correlating Ebsd And Afm Data Arrays, Andrew Krawec, Matthew Michie, John Blendell

The Summer Undergraduate Research Fellowship (SURF) Symposium

Ceramic and semiconductor research is limited in its ability to create holistic representations of data in concise, easily-accessible file formats or visual data representations. These materials are used in everyday electronics, and optimizing their electrical and physical properties is important for developing more advanced computational technologies. There is a desire to understand how changing the composition of the ceramic alters the shape and structure of the grown crystals. However, few accessible tools exist to generate a dataset with the proper organization to understand correlations between grain orientation and crystallographic orientation. This paper outlines an approach to analyzing the crystal structure …

Design Of Lattice Structures With Graded Density Fabricated By Additive Manufacturing, Wenjin Tao, Yong Liu, Austin T. Sutton, Krishna C. R. Kolan, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Lattice structures fabricated by Additive Manufacturing (AM) processes are promising for many applications, such as lightweight structures and energy absorbers. However, predicting and controlling of their mechanical behaviors is challenging due to the complexity of modeling and the uncertainties exist in the manufacturing process. In this paper, we explore the possibilities enabled by controlling the local densities. A set of lattice structures with different density gradients are designed using an implicit isosurface equation, and they are manufactured by Selective Laser Melting (SLM) process with 304L stainless steel. Finite element analysis and compression test are used to evaluate their mechanical properties. …

Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 1100°C In Air And In Silicic Acid-Saturated Steam, Logan M. Gumucio

Theses and Dissertations

Innovations in SiC based ceramic matrix composites (CMCs) have yielded exceptional high-temperature properties and performance in aggressive oxidizing environments. These material characteristics provide potential avenues for future advancements in many applications where current metallic alloys perform near their operating temperature limits in a harsh environment. As steam (typically present in these environments) enters through cracks in the matrix of a SiC/SiC composite, it leaches Si and becomes saturated with silicic acid, Si(OH)₄, prior to attacking the reinforcing SiC fibers. Therefore, it is paramount that a thorough understanding of the performance and durability of SiC fibers be obtained under …

Materials Design With Polylactic Acid-Polyethylene Glycol Blends Using 3d Printing And For Medical Applications., Jeremiah R. Bauer

Electronic Theses and Dissertations

This thesis is an examination of two material systems derived from polylactic acid (PLA) and polyethylene glycol (PEG). PLA is a polymer commonly sourced from renewable sources such as starches and sugars. It is a relatively strong, biodegradable polymer, making it ideal for use in the body. Even though it has a relative high strength, PLA is also brittle leading to the use of plasticizers to increase flexibility. One such plasticizer is PEG, which is a material that can exist at room temperature as either a thin liquid, or a hard waxy solid depending on the molecular weight. The first …

Creep Of Hafnium Diboride -20 Vol% Silicon Carbide At 1500°C In Air, Glen E. Pry

Theses and Dissertations

Refractory metal borides, commonly referred to as Ultra High Temperature Ceramics (UHTCs), exhibit a number of unique properties, such as extremely high melting temperature and hardness, chemical stability, high electrical and thermal conductivity and corrosion resistance. It has been demonstrated that the addition of SiC improves the oxidation resistance of ZrB2- and HfB2-based UHTCs above 1200°C by modifying the composition of the oxide scale. Addition of SiC retards the oxidation rate of ZrB2 and HfB2 by forming a protective layer of borosilicate glass. Creep deformation is one of the critical criterion for structural application of ceramics at elevated temperatures. Compression …

Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 1000°C In Air And In Silicic Acid-Saturated Steam, Brian G. Kroeger

Theses and Dissertations

Advanced SiC/SiC ceramic matrix composites (CMCs) are being considered for a variety of applications. Of interest is their ability to withstand exposure to high temperature in an aggressive oxidizing environment. The presence of steam creates such an environment. As steam traverses across a SiC/SiC composite and through cracks in the SiC matrix, it becomes saturated with silicic acid, Si(OH)₄. It is essential to understand the long-term impacts and durability of SiC/SiC CMCs that have been exposed to such a demanding environment. The present research investigated creep of Hi-Nicalon™ S SiC fibers at 1000°C in air and in silicic …

Multifunctional Cerium-Based Nanomaterials And Methods For Producing The Same, Matthew O'Keefe, William Fahrenholtz, Carlos E. Castano Londono

Materials Science and Engineering Faculty Research & Creative Works

Embodiments relate to a cerium-containing nano-coating composition, the composition including an amorphous matrix including one or more of cerium oxide, cerium hydroxide, and cerium phosphate; and crystalline regions including one or more of crystalline cerium oxide, crystalline cerium hydroxide, and crystalline cerium phosphate. The diameter of each crystalline region is less than about 50 nanometers.

A Preliminary Study Of Smithport Plain Bottle Morphology In The Southern Caddo Area, Robert Z. Selden Jr.

CRHR: Archaeology

This study expands upon a previous analysis of the Clarence H. Webb collection, which resulted in the identification of two discrete shapes used in the manufacture of the base and body of Smithport Plain bottles. The sample includes the Smithport Plain bottles from the Webb collection, and four new bottles: two previously repatriated specimens in the Pohler Collection, and two from the Mitchell site (41BW4) to test whether those specimens align morphologically with the Belcher Mound or Smithport Landing specimens. Results indicate significant allometry and a significant difference in Smithport Plain body and base shapes for bottles produced at the …

Surfactant Driven Assembly Of Freeze-Casted, Polymer-Derived Ceramic Nanoparticles On Grapehene Oxide Sheets For Lithium-Ion Battery Anodes, Ali Zein Khater

Honors Undergraduate Theses

Traditional Lithium-Ion Batteries (LIBs) are a reliable and cost-efficient choice for energy storage. LIBs offer high energy density and low self-discharge. Recent developments in electric-based technologies push for replacing historically used Lead-Acid batteries with LIBs. However, LIBs do not yet meet the demands of modern technology. Silicon and graphene oxide (GO) have been identified as promising replacements to improve anode materials. Graphene oxide has a unique sheet-like structure that provides a mechanically stable, light weight material for LIB anodes. Due to its structure, reduced graphene oxide (rGO) is efficiently conductive and resistive to environmental changes. On the other hand, silicon-based …

Femtosecond Laser-Matter Interactions In Ternary Zinc Phosphate Glasses, J. Hernandez-Rueda, N. W. Troy, P. Freudenberger, Richard K. Brow, D. M. Krol

Materials Science and Engineering Faculty Research & Creative Works

We investigate the interaction of ultrashort laser pulses with ternary zinc phosphate glasses. We explore the viability of ten different glass compositions with different levels of alumina to inscribe optical waveguides via the fs-laser direct writing technique, finding that only samples with [O]/[P] ratios of 3.25 are suitable candidates. We also test a zinc magnesium phosphate glass to fabricate waveguide Bragg gratings in order to generate filters and mirrors with specific spectral properties. Confocal Raman spectroscopy inspection shows that laser-damaged material exhibits a relative intensity decrease and a subtle blue-shift on the 1209 cm-1 Raman peak, which implies a relative …

Processing Of Cubic Stabilized Zirconia Electrolyte Membranes For Electrolyte-Supported Single Cell Solid Oxide Fuel Cells Using Tape Casting, Arturo Coronado Rodriguez

Honors Undergraduate Theses

Electrochemical conversion devices are a developing technology that prove to be a viable and more efficient alternative to current environmentally friendly generation devices. As such, constant research has been done in the last few decades to increase their applications and reliability. One of these systems, and the focus of this research, is the single cell Solid Oxide Fuel Cell (SOFC). These systems are a developing technology which main caveat is the need of high operating temperatures and costs. As such, most multidisciplinary research has been focused on researching materials and/or processes that help mitigate the costs or lower the operating …

Equibiaxial Flexural Strength Testing Of Advance Ceramics, Ryan T. Jordan

Honors Undergraduate Theses

Ceramics are very important materials with many unique properties used in numerous industrial applications. Ceramics could be very hard and very strong in comparison to metals; however, they are very brittle, thus they are prone to instantaneous and catastrophic failure. Therefore, their reliability is compromised and it is very important to have advanced techniques that allow evaluating their mechanical behavior in many unusual stress states. One of such testing methods is biaxial strength method, that allows to measure properties not only unidirectional, but also in a biaxial way. The research work for this thesis will be built on design and …

Raman Spectroscopy Of The Skeleton Of The Coral Acropora Cervicornis, Zachary C. Shepard

Honors Undergraduate Theses

Coral reefs are an important element of marine ecosystem that are critical to maintain a healthy environment. Unfortunately, in recent years coral reefs are doing poorly and many in parts of the ocean are simply dying. Therefore, study of coral’s structural response to external loads could answer what will happen with their structures, while they exhibit different types of loading. Therefore, the proposition of using in-situ micro-Raman spectroscopy to study skeletons of Acropora cervicornis was used. Coral skeleton samples I subjected to mechanical loading studied their vibrational properties by exciting the material with 532nm visible light. A uniaxial compressive load …

Optimal Sintering Temperature Of Ceria-Doped Scandia Stabilized Zirconia For Use In Solid Oxide Fuel Cells, Amanda K. Assuncao

Honors Undergraduate Theses

Carbon emissions are known to cause decay of the Ozone layer in addition to creating pollutant, poisonous air. This has become a growing concern among scientists and engineers across the globe; if this issue is not addressed, it is likely that the Earth will suffer catastrophic consequences. One of the main culprits of these harmful carbon emissions is fuel combustion. Between vehicles, power plants, airplanes, and ships, the world consumes an extraordinary amount of oil and fuel which all contributes to the emissions problem. Therefore, it is crucial to develop alternative energy sources that minimize the impact on the environment. …

Assisted Development Of Mesophase Pitch With Dispersed Graphene And Its Resulting Carbon Fibers, Aaron Owen

Theses and Dissertations--Mechanical and Aerospace Engineering

The efficacy of dispersed reduced graphene oxide (rGO) as a nucleation site for the growth of mesophase in an isotropic pitch was investigated and quantified in this study. Concentrations of rGO were systematically tested in an isotropic petroleum and coal-tar pitch during thermal treatments and compared to pitch without rGO. The mesophase content of each thermally treated pitch was quantified by polarized light point counting. Further characterization of softening temperature and insolubles were quantified. Additionally, the pitches with and without rGO were melt spun, graphitized, and tensile tested to determine the effects of rGO on graphitized fiber mechanical properties and …

Defect Chemistry And Transport Properties Of Solid State Materials For Energy Storage Applications, Xiaowen Zhan

Theses and Dissertations--Chemical and Materials Engineering

Replacing organic liquid electrolytes with nonflammable solid electrolytes can improve safety, offer higher volumetric and gravimetric energy densities, and lower the cost of lithium-ion batteries. However, today’s all-solid-state batteries suffer from low Li-ion conductivity in the electrolyte, slow Li-ion transport across the electrolyte/electrode interface, and slow solid-state Li-ion diffusion within the electrode. Defect chemistry is critical to understanding ionic conductivity and predicting the charge transport through heterogeneous solid interfaces. The goal of this dissertation is to analyze and improve solid state materials for energy storage applications by understanding their defect structure and transport properties.

I have investigated defect chemistry of …

Inorganic Biodegradable Substrates For Devices And Systems, Chang-Soo Kim, Richard K. Brow, D. E. Day

Electrical and Computer Engineering Faculty Research & Creative Works

Disclosed are biodegradable glass substrates that are useful as functional elements of solid-state devices. In particular, biodegradable glass substrates having a rapidly degradable glass and a slowly degradable glass provide a structural platform that completely dissolves following a desired operational lifetime of devices such as implanted electronic devices, implanted sensor devices, and optical fibers.

Material Properties Design Using Simulations And Experiments For Powder Injection Molding Of Lead Zirconate Titanate (Pzt)., Bhushan Pramod Bandiwadekar

Electronic Theses and Dissertations

Powder injection molding (PIM) process simulations can be performed to minimize the number of injection molding experiments by estimating material properties necessary for PIM simulations. In current work, lead zirconate titanate (PZT) powder-polymer binder feedstock was compounded for 45 vol. % and 52 vol. % solids loading. PIM experiments on designed micro-pillar array geometry were performed using 52 vol. % PZT. Using PIM experiments results as basis, PIM simulations were performed on designed micro-pillar array geometries to understand the effectiveness of PIM simulations with the use of estimated feedstock properties in predicting molding behavior that have micro-features. Additionally, PIM simulations …