Ceramic Materials Commons^™

Biodegradable Composite Scaffold For Repairing Defects In Load-Bearing Bones, D. E. Day, Ali Mohammadkhah

Materials Science and Engineering Faculty Research & Creative Works

A tissue scaffold for repair and regeneration of bone hard tissue or muscle, skin, or organ soft tissue, including load-bearing bone tissue, the scaffold comprising a core of biocompatible, biodegradable inorganic glass fibers; and a biocompatible, biodegradable, flexible polymer film surrounding the core and adhered to the core.

Creep Of Nextel 720/Alumina Ceramic Matrix Composite With Diamond-Drilled Effusion Holes At 1200°C In Air And In Steam, Megan L. Harkins

Theses and Dissertations

A recent study evaluated tensile stress-strain and tensile creep behavior of an oxide-oxide composite (Nextel™720/alumina) with laser-drilled effusion holes at 1200°C. It was determined that the presence of laser-drilled holes degraded the mechanical properties and performance of the CMC as a result of damage caused to the composite microstructure by the laser drilling process. Based on these results, the present effort sought to assess the effects of diamond-drilled holes on the mechanical behavior of this CMC. Tensile properties of the N720/A composite at 1200°C in laboratory air were unaffected by the presence of an array of 17 diamond-drilled effusion holes. …

Interlaminar Shear Performance Of High Temperature Composites, Tyler A. Wallis

Theses and Dissertations

Interlaminar shear properties of a high temperature polymer matrix composite (HTPMC) and a ceramic matrix composite (CMC) were evaluated at elevated tempera- ture. Two variants of the HTPMC were studied. Both consisted of a high-temperature polyimide (AFR-PE-4) matrix reinforced with Astroquartz-III pre-impregnated glass fabric woven in an eight-harness-satin weave. The first HTPMC variant also contained stainless steel foil at the midplane, while the second HTPMC variant did not. The interlaminar shear strength (ILSS) of both variants of the HTPMC was evaluated at 204°C in laboratory air. The addition of the stainless steel foil resulted in significant loss of ILSS for …

Ballistic Evaluation Of Carbon Nanotube Sheet Material In Multifunctional Applications, Casey M. Keilbarth

Theses and Dissertations

Significant development of carbon nanotubes has occurred since they were first studied in the 1990's. Attempts to capture the phenomenal molecular properties in practical applications are gaining ground as new methods of producing CNTs have been developed. This thesis sought to determine if the addition of commercially produced CNT sheets to thin carbon fiber panels improved the ballistic properties of the panel. The difference between 0 and 4 CNT sheets was studied. The hypothesis was that inte- grating CNT sheets into the laminate would increase the projectile energy absorbed by the panel and reduce the damage to the panel incurred …

Quantitative Probing Of Vacancies And Ions Dynamics In Electroactive Oxide Materials, Jiaxin Zhu

Doctoral Dissertations

Oxygen vacancy and ion dynamics in functional oxides are critical factors influencing electrical conductivity and electrochemical activity of oxides assemblies. The recent advancements in deposition and fabrication of oxide heterostructured films with atomic-level precision has led to discovery of intriguing physical properties and new artificial materials. While still under debate, researchers most often attribute these observed behaviors to unique oxygen vacancy distributions in the substrate near heterointerfaces. In electroactive oxides devices such as solid oxide cells (SOCs), oxygen vacancy and ion transport at the triple-phase boundary determines the performance of the device. This complex process motivates numerous remaining questions regarding …

Direct Patterning Of Nature-Inspired Surfaces For Biointerfacial Applications, Feyza Dundar

Doctoral Dissertations

There are three major challenges for the design of patterned surfaces for biointerfacial applications: (i) durability of antibacterial/antifouling mechanisms, (ii) mechanical durability, and (iii) lifetime of the master mold for mass production of patterned surfaces. In this dissertation, we describe our contribution for the development of each of these challenges. The bioinspired surface, Sharklet AF^TM, has been shown to reduce bacterial attachment via a biocide-free structure-property relationship effectively. Unfortunately, the effectiveness of polymer-based sharkskin surfaces is challenged over the long term by both eventual bacteria accumulation and a lack of mechanical durability. To address these common modes of …

Investigation Of Transition-Metal Ions In The Nickel-Rich Layered Positive Electrode Materials For Lithium-Ion Batteries, Shuang Gao

Theses and Dissertations--Chemical and Materials Engineering

Layered lithium transition-metal oxides (LMOs) are used as the positive electrode material in rechargeable lithium-ion batteries. Because transition metals undergo redox reactions when lithium ions intercalate in and disintercalate from the lattice, the selection and composition of transition metals largely influence the electrochemical performance of LMOs. Recently, a Ni-rich compound, LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811), has drawn much attention. It is expected to replace its state-of-the-art cousins, LiCoO₂ (LCO) and LiNi_1/3Co_1/3Mn_1/3O₂ (NCM111), because of its higher capacity, lower cost, and reduced toxicity. However, the excess Ni, as a …

Compositional Analysis Of Cerium And Cesium In Rapid Setting Cement As An Immobilization Agent For Nuclear Waste, Riyadh M. Motny

Theses and Dissertations

A feasibility of rapid setting cement (RSC) as an agent of immobilization for certain elements such as fission products or radioactive materials was explored. Cerium (Ce) and cesium (Cs) have been selected as a surrogate for U and/or Pu and fission products, respectively, in this study in three phases. In Phase I, RSC was evaluated for physical properties (e.g., porosity, density, pH values, etc.) using two groups methods—the cement powder at different concentrations of Ce (2 – 10 wt%) with deionized water (DIW) and artificial seawater (ASW). The results showed that the final setting time and compressive strength of RSC …

Experimental And Numerical Simulation Of Split Hopkinson Pressure Bar Test On Borosilicate Glass, Mayank K. Bagaria

Dissertations, Master's Theses and Master's Reports

This study is an extension to the design of ceramic materials component exposed to bullet impact. Owing to the brittle nature of ceramics upon bullet impact, shattered pieces behave as pellets flying with different velocities and directions, damaging surrounding components. Testing to study the behavior of ceramics under ballistic impact can be cumbersome and expensive. Modeling the set-up through Finite Element Analysis (FEA) makes it economical and easy to optimize. However, appropriately incorporating the material in modeling makes laboratory testing essential. Previous efforts have concentrated on simulating crack pattern developed during 0.22 caliber pellet impact on Borosilicate glass. A major …

Metallic Systems At The Nano And Micro Scale: Bimetallic Nanoparticles As Catalysts And Mcraly Bond Coats In Thermal Barrier Coatings, Kenneth Kane

Theses and Dissertations

The dissertation is split into two parts. The first part will be focused on changes in material properties found at the nanoscale, as miscibility and electronic structure can change significantly with size. The formation of classically-immiscible bimetallic nanoparticles (BNPs) becomes favorable at the nanoscale and novel catalytic properties can emerge from the bimetallic alloying. The formation of alloyed and non-alloyed BNPs is achieved through pulse laser ablation (PLA) and a significant increase in catalytic activity is observed for both. Recently discovered, the increased activity in the non-alloyed BNPs, deemed multicomponent photocatalysis, is examined and the proposed mechanism discussed. The second …

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

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 …

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 …

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 …

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

Graduate Theses, Dissertations, and Problem Reports

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 …

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

Graduate Theses, Dissertations, and Problem Reports

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 …}

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

McKelvey School of Engineering 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 …

Fabrication Of High Refractive Index, Periodic, Composite Nanostructures For Photonic And Sensing Applications, Irene Howell

Doctoral Dissertations

This dissertation examines methods of fabricating high refractive index, periodic structures and their applications. Structures with a refractive index periodicity in one-dimensionally are fabricated by stacking layers of (high-refractive index) nanoparticle-filled and unfilled layers. More complex two- and three-dimensional structures are fabricated by direct printing of nanoparticles via solvent-assisted soft nanoimprint lithography. Polymer-nanoparticle composites are an active area of research and development especially for photonic applications. We show use of two composite formulations, first for fabrication of one-dimensional photonic crystals, and second for scalable UV-nanoimprinting. One dimensional photonic crystals, which possess a periodicity in refractive index, result in a constructive …