Materials Science and Engineering Commons^™

Section Abstracts: Astronomy, Mathematics And Physics With Material Science

Virginia Journal of Science

Abstracts of the Astronomy, Mathematics, and Physics with Material Science Section for the 93rd Annual Meeting of the Virginia Academy of Science, May 21-23, 2015, James Madison University, Richmond, Virginia

High Pressure Behavior Of Mullite-Type Oxides: Phase Transitions, Amorphization, Negative Linear Compressibility And Microstructural Implications, Patricia Kalita

UNLV Theses, Dissertations, Professional Papers, and Capstones

Even though mullite occurs rarely in nature, it is perhaps one of the most important phases in both traditional and advanced ceramics. Existing and emerging applications of mullite and mullite-type materials include: high-temperature composites, aerospace materials, ballistic shielding for military applications and even non-linear optical materials. There are many uncertainties regarding the basic physical properties of mullite-type materials, particularly in terms of their high-pressure structural stability and mechanical behavior that are important to address for emerging applications of mullites as engineering materials. This work is the first reported comprehensive investigation of the high –pressure structural behavior of several different mullites …

Molecular Dynamics Simulation Of Irradiation Damage In Multicomponent Alloys, Wei Guo

Doctoral Dissertations

The development of the generation IV reactors calls for radiation resistant materials. This thesis proposes that the newly developed single phase solid solution of high-entropy alloys (HEAs) can be such candidates. HEAs can undergo the crystalline to amorphous to crystalline (C-A-C) transitions under radiation. The radiation induced amorphous structure is a highly radiation resistant medium as shown by previous studies, and it further transforms to crystalline phases without much structural defects. In this thesis, by reviewing the formation rules of solid solutions and amorphous metallic glasses, it is suggested that the atomic size plays a key role affecting the C-A-C …

Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, Robin Woracek

Doctoral Dissertations

This multipart dissertation focuses on the development and evaluation of advanced methods for material testing and characterization using neutron diffraction and imaging techniques. A major focus is on exploiting diffraction contrast in energy selective neutron imaging (often referred to as Bragg edge imaging) for strain and phase mapping of crystalline materials. The dissertation also evaluates the use of neutron diffraction to study the effect of multi-axial loading, in particular the role of applying directly shear strains from the application of torsion. A portable tension-torsion-tomography loading system has been developed for in-situ measurements and integrated at major user facilities around the …

Cure Kinetics, Morphologies, And Mechanical Properties Of Thermoplastic/Mwcnt Modified Multifunctional Glassy Epoxies Prepared Via Continuous Reaction Methods, Xiaole Cheng

Dissertations

The primary goal of this dissertation is to develop a novel continuous reactor method to prepare partially cured epoxy prepolymers for aerospace prepreg applications with the aim of replacing traditional batch reactors. Compared to batch reactors, the continuous reactor is capable of solubilizing and dispersing a broad range of additives including thermoplastic tougheners, stabilizers, nanoparticles and curatives and advancing epoxy molecular weights and viscosities while reducing energy consumption.

In order to prove this concept, polyethersulfone (PES) modified 4, 4’-diaminodiphenylsulfone (44DDS)/tetraglycidyl-4, 4’-diaminodiphenylmethane (TGDDM) epoxy prepolymers were firstly prepared using both continuous reactor and batch reactor methods. Kinetic studies confirmed the chain …

Methods For Growing Retinal Pigment Epithelial Cells: Current Protocols And Future Recommendations, Aaron H. Fronk

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The retinal pigment epithelium (RPE) is a layer of tissue found in the vertebrate eye between Bruch’s membrane and the photoreceptor layer of the neural retina [1]. It is derived from the outer layer of the optic cup [2], possesses an innate immune system [3], and consists of a monolayer of highly pigmented cells that fit together in a tight matrix (fig. 1) [4]–[6]. The monolayer is often compared to a mosaic or cobblestones in its configuration, while the shape of the individual cells is usually described as polygonal/hexagonal, columnar (aligned perpendicular to the underlying membrane), or “epithelioid”. The cells …

Designing A Clarifier To Recover Wastewater Algae Biomass For Production Of Biofuels, Elizabeth Martinez

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The Logan Lagoons, Logan City’s Wastewater Treatment Facility ensures 15 million gallons of wastewater are cleaned and filtered each day. With the implementation of new and stricter wastewater effluent standards, the city of Logan now has to guarantee the phosphorous concentration in the effluent is also reduced. Algal biomass produced and harvested from the lagoons has been proven to affect the way nitrogen and phosphorous are removed, while having the potential to be converted to biofuels. Therefore, implementing a secondary type clarifier in the Logan Lagoons would produce treated water with a reduced phosphorous concentration, and algae feedstock for biofuel …

Novel Two-Dimensional Nanomaterials And Their Gas Sensing Properties, Haihui Pu

Theses and Dissertations

Graphene, an atomic thin two-dimensional (2D) material with C atoms arranged in a honeycomb lattice, has sparked an unprecedented research interest across various scientific communities since its initial mechanical isolation in 2004. The linear energy dispersion with respect to the momentum within 1 eV around the Fermi level at the high symmetric K (Dirac) points in the Brillouin zone renders graphene a wonder material for scientists. However, graphene’s semimetallic nature significantly limits its high-end applications, e.g., in digital logic circuits. Therefore, continued efforts in opening the band gap for graphene and in searching for novel 2D semiconducting materials are rewarding. …

Reaction Kinetics Of Rare Earth And Actinide Materials, Brian Jon Jaques

Boise State University Theses and Dissertations

This dissertation presents the effects of atmosphere, time, and energy input (thermal and mechanical) on the kinetics of gas-solid and solid-solid reactions in systems of dysprosium, uranium, oxygen, and nitrogen. Accordingly, Chapter Two presents a novel synthesis technique used to form DyN via a gas-solid reaction between dysprosium and nitrogen. DyN was rapidly formed through a mechanochemical process in a high energy ball mill at ambient temperatures. The progress of the reaction was quantified using in situ temperature and pressure measurements coupled with microscopy and x-ray diffraction. It was found that the rate of the nitridation reaction is controlled by …

Erratum: "Impact Of Symmetry On The Ferroelectric Properties Of Catio₃ Thin Films" (Applied Physics Letters 106:162904 (2015)), Michael D. Biegalski, Liang Qiao, Yijia Gu, Apurva Mehta, Qian He, For Full List Of Authors, See Publisher's Website.

Materials Science and Engineering Faculty Research & Creative Works

There is a typo of the space group. All the Pnmb should be Pbnm (or Pnma). So the Glazer notation should be changed to (a^-a^-c⁺) for Pbnm space group on page 4 of the article. We have also noticed that the thermodynamic analysis of CaTiO₃ thin film is not correct. The films are (001)_PC-oriented or (101)-oriented. Therefore, there is no need to rotate the coordinate system (on page 4 of the article). By applying the thin film boundary condition, i.e., ε₁₁ = ε₂₂ = ε_s, ε …

Origin Of Interfacial Polar Order In Incipient Ferroelectrics, Yijia Gu, Nan Wang, Fei Xue, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

There are ample experimental evidences indicating that the ferroelastic domain walls of incipient ferroelectrics, such as SrTiO₃ and CaTiO₃, are polar. The emergence of such interfacial polar order at a domain wall is exciting and believed to arise from the coupling between a primary order parameter, such as a strain or an antiferrodistortive (AFD) order parameter, and polarization. There have been several mechanisms proposed to explain the emergence of interfacial polar order, including biquadratic coupling, AFD-antiferroelectric coupling, and flexoelectric coupling. Using CaTiO₃ as an example, we demonstrate, using both asymptotic analytics and numerical calculation, that the …

Characterization Of Microstructure And Property Evolution In Advanced Cladding And Duct: Materials Exposed To High Dose And Elevated Temperature, Janelle P. Wharry

Materials Science and Engineering Faculty Publications and Presentations

Designing materials for performance in high-radiation fields can be accelerated through a carefully chosen combination of advanced multiscale modeling paired with appropriate experimental validation. The studies reported in this work, the combined efforts of six universities working together as the Consortium on Cladding and Structural Materials, use that approach to focus on improving the scientific basis for the response of ferritic–martensitic steels to irradiation. A combination of modern modeling techniques with controlled experimentation has specifically focused on improving the understanding of radiation-induced segregation, precipitate formation and growth under radiation, the stability of oxide nanoclusters, and the development of dislocation networks …

Studies Of High Temperature Hydrogen Related Damage In Welded Carbon Steel Components Used In Refineries, Maneel Bharadwaj

Masters Theses

Five materials encompassing various grades of carbon steel were received from retired and ex-service petroleum refinery equipment for root-cause evaluation of High Temperature Hydrogen Attack (HTHA) damage at UTK. These materials were submitted by three contributors: Irving Oil Refinery (IOR #1110-2), Valero (#67 & #1252134), and Phillips 66 (#555-S1 & #555-S2) on behalf of American Petroleum Institute (API). These materials originated from various flange-to-pipe welded components that were exposed in hydrogen pressure environment at elevated temperatures (> 640°F and >70 psia).

A singular crack originating at the flange inside surface just outside of the visible HAZ was observed in IOR …

The Design Of High Performance And Ultra-High Performance Fiber Reinforced Cementitious Composites With Nano Materials, Scott W. Muzenski

Theses and Dissertations

The use of high performance and ultra-high performance cementitious composites (HPC/UHPC) in critical elements of infrastructure can be a sustainable alternative to conventional concrete. These materials provide superior durability, reducing the need for maintenance and early replacement. The use of special cements and nano-materials improve the strength and durability of HPC/UHPC composites by providing a denser microstructure. The addition of high performance fibers enhances the ductility and restricts the crack size, reducing water penetration in cracked material. In HPC, the addition of superhydrophobic admixtures further reduces water permeability and thus provides superior durability and freeze-thaw resistance by producing a preferred …

Characterization Of Silicon Phosphorus Alloy For Device Applications, Larry C. Cousar

Graduate Theses and Dissertations

A new material of highly-phosphorus doped silicon for device applications was characterized and analyzed for new material properties. Devices such as NMOS transistors and other CMOS compatible devices may benefit from new materials that reduce external resistances and increase drive currents.

Material characterization requires numerous techniques and technologies to determine electrical, optical, and physical characteristics. For this work, Hall measurement, X-ray Diffraction, Raman Spectroscopy, Photoluminescence Characterization, and Spectroscopic Ellipsometry were used to better understand this new material. The results may lead to new models for silicon phosphorus alloys.

Large-Scale Graphene Film Deposition For Monolithic Device Fabrication, Khaled Al-Shurman

Graduate Theses and Dissertations

Since 1958, the concept of integrated circuit (IC) has achieved great technological developments and helped in shrinking electronic devices. Nowadays, an IC consists of more than a million of compacted transistors.

The majority of current ICs use silicon as a semiconductor material. According to Moore's law, the number of transistors built-in on a microchip can be double every two years. However, silicon device manufacturing reaches its physical limits. To explain, there is a new trend to shrinking circuitry to seven nanometers where a lot of unknown quantum effects such as tunneling effect can not be controlled. Hence, there is an …

Eye Tracking Consumer Purchase Behavior Within Physical And Virtual Environments, David Andrew Stone

All Theses

Understanding how consumers observe and make purchase decisions within a retail context is now both accessible and efficient through the process of eye tracking. Eye tracking package design aesthetics helps us understand and predict what consumers are looking at, and how likely a package might be selected. Typically, this research is conducted in an immersive retail setting where consumers can shop as they would in a normal store-shopping context. A store is stocked with products where a participant in the study shops throughout while wearing an eye tracker to gather data on what their attention fixates on within a given …

Material Coefficient Of Thermal Expansion Investigation For Use In Additive Manufacturing Fused Deposition Modeling For Composite Tooling, Daniel Joseph Miller

Master's Theses

Polymer matrix composites are being used to manufacture light weight, high stiffness aircraft structures. These structures are often manufactured from carbon fiber reinforced epoxy. When these structures are damaged, they must be repaired to restore strength to the component to avoid the cost and logistics of having replacements parts. Occasionally, these repairs require tooling in order to make a quality repair, however, tooling generally has a long lead time. Additive manufacturing could be used to manufacture rapid tooling to create tooling for composite repairs. The issue is that polymer printed tooling has a much higher coefficient of thermal expansion (CTE) …

Generalized Ellipsometry Analysis Of Anisotropic Nanoporous Media: Polymer-Infiltrated Nanocolumnar And Inverse-Column Polymeric Films, Dan Liang

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Characterization of the structural and optical properties is a subject of significance for nanoporous material research. However, it remains a challenge to find non-destructive methods for investigating the anisotropy of porous thin films with three-dimensional nanostructures. In this thesis, a generalized ellipsometry (GE) analysis approach is employed to study two types of anisotropic nanoporous media: slanted columnar thin films (SCTFs) with polymer infiltration and inverse-SCTF polymeric films. The thesis presents the physical properties obtained from GE analysis, including porosity, columnar shape, principal optical constants, birefringence, etc.

The thesis reports on using a GE analysis approach, combining the homogeneous biaxial layer …

Ultrahigh Density Sub-10 Nm Cobalt Nanowire Arrays: Simulation, Fabrication, And Characterization, Yuan Tian

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

The simulation, fabrication, and characterization of self-assembled ultrahigh density sub-10nm Co nanowire arrays are presented in this dissertation. The general phase separation nanowire growth simulation was operated based on a modified Ising model. The fabrication process can be summarized as the binary Co-X systems lateral phase separation during physical vapor deposition – the plasma layer deposition with a single alloy Co-X target. The “X” stands for Al or Si. The nanowire fabrication and diameter deduction was achieved by balancing the growth rate and surface diffusivity. For Co-Al binary system, the formed sub-10 nm Co nanowires are of face-centered cubic structure …