Materials Science and Engineering Commons^™

Experimental And Numerical Study Of Phase Transition Of Lifepo₄ Material In Lithium Ion Batteries, Md Noor E Alam Siddique

Material Science and Engineering Dissertations - Archive

Phase transition behavior of LiFePO4 material has been studied in this work. During electrochemical charge/discharge processes, LiFePO4 transforms into FePO4 and this electrochemically driven phase transition of the two-phase system results in a potential plateau in a battery discharge curve. Besides, battery performance, especially under high rates, depends critically on this two-phase transition. However, this phase transition mechanism in the LiFePO4 crystal structure has yet not been understood in details. Developing better understanding is essential for designing high performing, safe and stable batteries.Currently available phase transition models for LiFePO4, such as the classical `core-shrinking model' and recently the `domino cascade …

Early-Age Hydration Studies Of Portland Cement, Fengjuan Liu

Electronic Theses and Dissertations

Our current knowledge on cement hydration during setting is based on the discrete observation of hydrated paste. An advanced micro/nano-level technique which can perform the in-situ observation on the continuous hydration of cement paste is demanded. In this study, Raman spectroscopy (RS) was chosen as such a method to continuously investigate wet pastes. The objective of this research is to explore the hydration process and microstructural development of fresh pastes with this technique. This research was conducted in three phases. First, the RS analysis was used to continuously observe the cement hydration from 20 minutes after mixing to 9 hours. …

Slow Strain Rate Testing And Stress Corrosion Cracking Of Ultra-Fine Grained And Conventional Al–Mg Alloy, Mala M. Sharma, Josh D. Tomedi, Timothy J. Weigley

Faculty Journal Articles

Stress corrosion cracking susceptibility was investigated for an ultra-fine grained (UFG) Al–7.5Mg alloy and a conventional 5083 H111 alloy in natural seawater using slow strain rate testing (SSRT) at very slow strain rates between 1E⁻⁵ s⁻¹, 1E⁻⁶ s⁻¹ and 1E⁻⁷ s⁻¹. The UFG Al–7.5Mg alloy was produced by cryomilling, while the 5083 H111 alloy is considered as a wrought manufactured product. The response of tensile properties to strain rate was analyzed and compared. Negative strain rate sensitivity was observed for both materials in terms of the elongation to failure. However, the UFG …

Performance Analysis Of A Hybrid Raman Optical Parametric Amplifier In The O- And E-Bands For Cwdm Pons, Sasanthi Peiris, Nicolas Madamopoulos, Neophytos A. Antoniades, Dwight Richards, Roger Dorsinville

Publications and Research

We describe a hybrid Raman-optical parametric amplifier (HROPA) operating at the O- and E-bands and designed for coarse wavelength division multiplexed (CWDM) passive optical networks (PONs). We present the mathematical model and simulation results for the optimization of this HROPA design. Our analysis shows that separating the two amplification processes allows for optimization of each one separately, e.g., proper selection of pump optical powers and wavelengths to achieve maximum gain bandwidth and low gain ripple. Furthermore, we show that the proper design of optical filters incorporated in the HROPA architecture can suppress idlers generated during the OPA process, as well …

Corrosion Behaviour Of High Phosphorus Containing Cu-Cr Weather Resistant Steel, Gadadhar Sahoo, Anjana Deva, Balbir Singh, Atul Sexena

Journal of Metals, Materials and Minerals

Three steels viz., G22(Fe-0.072C-0.028 Si-0.20Mn-0.19P-0.38Cr-0.24Cu-0.17Ni), G32(Fe-0.072C-0.061 Si-0.23 Mn-0.19P-0.64Cr-0.14Cu) and SCOR (Fe-0.09C-0.37Si-0.42Mn-0.15P-0.37Cr-0.35Cu-0.31Ni) were made through ingot metallurgy route and hot rolled to 3 mm thick sheets. For other steels, similar corrosion rates were observed from the Tafel extrapolation study of freshly ground samples in 3.5% NaCl solution. Other technique employed to evaluate the effect of phosphorus on the formation of protective rust layer was electrochemical impedance spectroscopy (EIS) test after exposing the samples in an atmospheric exposure rack for four months on the roof top of a fourth floored building. Results revealed that the polarization resistance or rust resistance of G22 …

Effects Of Poly(Butylene Succinate) And Calcium Carbonate On The Physical Properties Of Plasticized Poly(Vinyl Chloride), Saowaroj Chuayjuljit, Phasawat Chaiwutthinan, Sitthipong Samutthong, Onusa Saravari, Anyaporn Boonmahitthisud

Journal of Metals, Materials and Minerals

In this studypoly(butylene succinate) (PBS) , a polymeric plasticizer, was partially replaced a conventional plasticizer, diisononyl phthalate (DINP) to avoid the plasticizer loss from poly(vinyl chloride) (PVC) overtime for various service conditions and to obtain a long-term plasticizer retention in the flexible PVC products. The plasticized PVC samples were prepared by melt mixing on a two roll mill, followed by compression molding. The mechanical properties (tensile properties, tear strength and hardness), thermal stability and morphology of the 20/20 phr (parts by weight per hundred parts of resin) DINP/PBS-plasticized PVC were evaluated and compared with those of the 40 phr DINP-plasticized …

Microstructural Development Of Galvanized Steels Prepared With Ni-P Electroless Deposited Pre-Coatings, Chulaluk Somphotch, Suparoek Henpraserttae, Ekasit Nisarattanaporn, Yuttanant Boonyongmaneerat

Journal of Metals, Materials and Minerals

An electroless pre-coating process is investigated as a possible method to prevent the sandelin effect, whereby steels containing silicon reacts rapidly with zinc during galvanization. From the microstructural and kinetics analysis, it is found that nickel-phosphorus electroless pre-coatings effectively serve as barriers to the reaction between Fe and Zn during galvanization, regardless of the silicon content in the steel substrates. Correspondingly, the coating thickness of the galvanized steels can be well-controlled.

Synthesis Of Porous Silica By Co-Micelle Emulsion Ternplating Technique Using Peg/Acrylamide And 2-(Acryloyloxy)-N,N,N-Trimethylethanaminium Chloride/Acrylamide As Templates, Iman Abdullah, Widyastuti Samadi, Arvinda Widyana, David Chandra Pandapotan, Ridla Bakri

Journal of Metals, Materials and Minerals

Co-micelle emulsion templating (co-MET) technique is a new method to synthesize uniform and ordered porous silica from tetraethylortosilicate precursor using double polymer as templates. In this study, co-MET technique was conducted by varying template type (namely PEG/acrylamide and 2(acryloyloxy)N,N,Ntrimethylethanaminium chloride/acrylamide) and percentage of polymer (2.5%, 5%, 10%, 15% and 20% for PEG and 0.5%, 1%, 2.5%, 5%, 10% for 2(acryloyloxy)N,N,Ntrimethylethanaminium chloride). The resulting porous silica were then characterized by SEM-EDS, BET and XRD to investigates the pore character and structure of silica. Based on SEM-EDS and BET analysis, it is shown that the amount and the type of polymer gave …

Mechanical Properties Of Poly(Lactic Acid) Composites Reinforced With Microfibrillated Cellulose Prepared Using High Speed Blending, Supachok Tanpichai, Jatuphorn Wootthikanokkhan

Journal of Metals, Materials and Minerals

Bamboo fibers, as a raw cellulose source, were used to prepare microfibrillated cellulose (MFC) using a high speed blender at 20,000 rpm for 60 min. Nanofibers with the width of less than 100 nm were disintegrated from the fibers. MFC networks were then prepared, and embedded in poly(lactic acid) resin using a compression molding at temperature of 180 C and a pressure of 10 MPa. Mechanical properties of poly(lactic acid) composites reinforced with MFC were investigated. The interaction between MFC fibrils and PLA resin was observed. As a result, Youngs modulus and tensile strength of the composites increased to 3.1 …

Microanalysis Of Polymer Chain Diffusion In Heat Seals, Russell Cooper

All Theses

Heat sealing is an integral method for the closure and protection of packaging. Previous work has shown that seal strength is developed by the interdiffusion of polymer chains within heat seals. Heat seals were made between two dissimilar materials. Poly(ethylene-co-acrylic acid) (EAA) was heat sealed to ionomer. Diffusion within the EAA-ionomer heat seals was estimated. The diffusion estimates were then related to resulting seal strength in the EAA-ionomer sealant system. Heated tooling sealing was utilized to make heat seals at 40 psi (275.79 kPa), 0.5 seconds, and a range of temperatures between 180˚F (82.22˚C) and 300˚F (148.89˚C). Scanning electron microscopy …

Fabrication And Characterization Of Magnetic Nanoparticle Composite Membranes, Akeem Cruickshank

All Theses

To effectively and accurately deliver drugs within the human body, both new designs and components for implantable micropumps are being studied. Designs must ensure high biocompatibility, drug compatibility, accuracy and small power consumption. The focus of this thesis was to fabricate a prototype magnetic nanoparticle membrane for eventual incorporation into a biomedical pump and then determine the relationship between this membrane deflection and applied pneumatic or magnetic force. The magnetic nanoparticle polymer composite (MNPC) membranes in this study were composed of crosslinked polydimethylsiloxane (PDMS) and iron oxide nanoparticles (IONPs). An optimal iron oxide fabrication route was identified and particle size …

Relationship Between Peel Force, Opening Force, And Burst Force For A Semi-Rigid Cup And Lid, Pre- And Post-Retort, Raj Navalakha

All Theses

This research determines if there is any relationship between the peel force, the opening force and the burst force for a semi-rigid cup and lid system, for pre- and post-retort conditions. It also compares the relationship (regression lines) between these forces pre- and post-retort. These seal results were studied by varying the sealing parameters of dwell time and temperature while keeping the pressure constant. Polypropylene cups and a peelable barrier retort lidding were used in this study. As compared to past research, a different peel testing technique was used to measure the peel and the opening force. The entire lid …

Printing Functional Electronic Circuits And Components, Ahmed Tausif Aijazi

Dissertations

The purpose of this study was to investigate the challenges in printing reliable multilayer flexible circuits, devices and components. Gravure was used as the primary printing process for this work, but due to some limitations of gravure, other printing methods were also investigated. At first a systematic study was done to determine the optimum parameters for the gravure printing of sub 50 micron lines. Commercially available silver nanoparticle inks were printed on a lab scale gravure printer, Accupress®. The highest resolution line that was electrically conductive was 36μm wide. The 9μm, 18μm and 27μm lines were printed but were not …

Investigation Of Fatigue Life And Fracture Mechanics Of Unconstrained Ni-Mn-Ga Single Crystals, Theodore Bryson Lawrence

Boise State University Theses and Dissertations

Ni-Mn-Ga is a magnetic shape memory alloy (MSMA) that exhibits large recoverable strains. The magnetic field induced strain (MFIS) occurs through twin boundary motion resulting in reorientation of the crystal structure, which is coupled to the magnetic moment of the material. The shape memory capabilities of the material make it promising for applications including microactuators, sensors, microfluid pumps, refrigeration, energy harvesting, and data storage.

In order for Ni-Mn-Ga to become a viable option for use in commercial applications the performance and reliability must be on par with industry standards. Ni‑Mn-Ga has been shown to achieve high cycles at low strains, …

Fatigue Damage Prognosis Of Internal Delamination In Composite Plates Under Cyclic Compression Loadings Using Affine Arithmetic As Uncertainty Propagation Tool, Audrey J-M Gbaguidi

Doctoral Dissertations and Master's Theses

Structural health monitoring (SHM) has become indispensable for reducing maintenance costs and increasing the in-service capacity of a structure. The increased use of lightweight composite materials in aircraft structures drastically increased the effects of fatigue induced damage on their critical structural components and thus the necessity to predict the remaining life of those components. Damage prognosis, one of the least investigated fields in SHM, uses the current damage state of the system to forecast its future performance by estimating the expected loading environments. A successful damage prediction model requires the integration of technologies in areas like measurements, materials science, mechanics …

Composite Films With Magnetic Nanorods: Fundamentals, Processing And Applications, Yu Gu

All Dissertations

This Dissertation is centered on studying the composite films with magnetic nanorods. In recent years, one-dimensional magnetic nanostructures, such as magnetic nanorods, chains of magnetic nanoparticles, and nanotubes filled with magnetic nanoparticles have caught great attentions due to the breadth of applications. Their unique magnetic and geometrical features open new avenues of studies in medicine, sensors, optofluidics, magnetic swimming, and microrheology. In particular, they offered great opportunities for design of multifunctional devices and for manufacturing of anisotropic nano- and microstructures with unprecedented magnetic and mechanical properties. However, the strategy for nanorod alignment in both Newtonian and complex fluids has not …

Earth Abundant Thin Film Technology For Next Generation Photovoltaic Modules, Githin Alapatt

All Dissertations

With a cumulative generation capacity of over 100 GW, Photovoltaics (PV) technology is uniquely poised to become increasingly popular in the coming decades. Although, several breakthroughs have propelled PV technology, it accounts for only less than 1% of the energy produced worldwide. This aspect of the PV technology is primarily due to the somewhat high cost per watt, which is dependent on the efficiency of the PV cells as well as the cost of manufacturing and installing them. Currently, the efficiency of the PV conversion process is limited to about 25% for commercial terrestrial cells; improving this efficiency can increase …

Synthesis And Characterization Of Chemically Functionalized Shape Memory Nanofoams For Unattended Sensing Applications, Anna Paola Soliani

All Dissertations

The work in this dissertation is devoted to the synthesis and characterization of novel materials for off-line unattended sensing: shape-memory grafted nanofoams. The fabrication process and characterization of highly efficient, polymeric nanosensor element with the ability to selectively detect analytes and retain memory of specific exposure events is reported. These shape memory nanofoams could potentially act as efficient and highly sensitive coatings for evanescent waveguide-based optical monitoring systems. On exposure to specific analytes, the polymeric coatings locally change their internal structure irreversibly at the nanolevel, affecting the local optical properties such as refractive index. Currently, enrichment polymer layers (EPLs) are …

Effect Of Styrene-Methyl Methacrylate/Styrene-Butadiene Rubber On Properties Of Poly(Vinyl Chloride), Buranin Saengiet, Fuangfa Unob, Kawee Srikulkit

Journal of Metals, Materials and Minerals

Generally, poly(vinyl chloride) (PVC) without the addition of plasticizer or impact modifiers is rigid and brittle. The aim of this research was to improve the mechanical properties of PVC using styrene-methyl methacrylate/styrene-butadiene compound (SMMA/SBR rubber) as an impact modifier. The compound was obtained commercially. PVC containing SMMA/SBR rubber having SMMA/SBR phrs of 2.5, 5, 7.5 and 10 were prepared using two-roll mill set the conditions as follows: 170 oC and 5 min. Then, compression molding was carried out to prepare testing samples. FTIR analysis of SMMA/SBR rubber containing PVC samples showed the absorption band at 1732 cm-1 (C=O stretching), 3025 …

Effect Of Surfactant On Conductivity Of Poly(Pyrrole-Co-Formyl Pyrrole) Via Emulsion Polymerization, Sirilak Arunsawad, Kawee Srikulkit, Sarintorn Limpanart

Journal of Metals, Materials and Minerals

P(Py-co-FPy) were synthesized via emulsion polymerization, SDS and PSS used as surfactant and TFA as catalyst. Amounts of surfactant were vary as mole ratio of surfactant : monomer (0.25, 0.5 and 1.0). The synthesis copolymers were characterized by FTIR, SEM, particle size analyzer and four point probes. As a result of FT-IR spectra proved that the synthesized copolymers are associated with the structure of the P(Py-co-FPy). Spherical particles were detected by SEM and particles diameter is in range of 60-600 nm depending on type and amounts of surfactant. The electrical conductivity is in the range of 1.74x 10-5 to 2.21 …

Utilization Of Aqueous Raft Prepared Copolymers To Improve Anticancer Drug Efficacy, Andrew Christopher Holley

Dissertations

The advent of controlled radical polymerization (CRP) techniques, along with advancements in facile conjugation chemistry, now allow synthetic tailoring of precise, polymeric architectures necessary for drug/gene delivery. Reversible addition- fragmentation chain transfer (RAFT) polymerization and its aqueous counterpart (aRAFT) afford quantitative control over key synthetic parameters including block length, microstructure, and placement of structo-pendent and structo-terminal functionality for conjugation of active agents and targeting moieties. The relevance of water-soluble and amphiphilic (co)polymers synthesized by RAFT for in vitro delivery of therapeutics in biological fluids is an especially attractive feature. In many cases, polymerization, binding, conjugation, …

Orientations Of Low-Energy Domain Walls In Perovskites With Oxygen Octahedral Tilts, Fei Xue, Yijia Gu, Linyun Liang, Yi Wang, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

Many applications of ferroic materials, such as data storage and spintronics, are achieved through the control and manipulation of their domain wall (DW) orientations and configurations. Here we propose a rotational compatibility condition to identify low-energy DWs in perovskites with oxygen octahedral tilt instability. It is derived from the strong DW energy anisotropy arising from the rigidity and corner-sharing feature of the octahedral network. We analyze quantitatively the DWs in SrTiO₃ and explain successfully the unusual ferroelectric DW width and energy in BiFeO₃.

Low Molecular Weight Glucosamine/L-Lactide Copolymers As Potential Carriers For The Development Of A Sustained Rifampicin Release System: Mycobacterium Smegmatis As A Tuberculosis Model, Jorge Ragusa

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Tuberculosis, a highly contagious disease, ranks as the second leading cause of death from an infectious disease, and remains a major global health problem. In 2013, 9 million new cases were diagnosed and 1.5 million people died worldwide from tuberculosis. This dissertation aims at developing a new, ultrafine particle-based efficient antibiotic delivery system for the treatment of tuberculosis. The carrier material to make the rifampicin (RIF)-loaded particles is a low molecular weight star-shaped polymer produced from glucosamine (molecular core building unit) and L-lactide (GluN-LLA). Stable particles with a very high 50% drug loading capacity were made via electrohydrodynamic atomization. Prolonged …

Microstructure And Magnetic Behavior Studies Of Processing-Controlled And Composition-Modified Fe–Ni And Mn–Al Alloys, Yunlong Geng

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

L1₀-type (Space group P4/mmm) magnetic compounds, including FeNi and MnAl, possess promising technical magnetic properties of both high magnetization and large magnetocrystalline anisotropy energy, and thus offer potential in replacing rare earth permanent magnets in some applications.

In equiatomic Fe-Ni, the disorder-order transformation from fcc structure to the L1₀ structure is a diffusional transformation, but is inhibited by the low ordering temperature. The transformation could be enhanced through the creation of vacancies. Thus, mechanical alloying was employed to generate more open-volume defects. A decrease in grain size and concomitant increase in grain boundary area resulted from …

High Strength Steel Fiber Reinforced Flow-Able Or Scc Concrete With Variable Fiber By Volume Fractions For Thin Plate And Shell Structures, Abebe Berhe

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to incorporate discrete, short, mechanically deformed, small diameter steel fibers into high strength concrete with f'c > 70 MPa (10 ksi) in an attempt to reduce and partially eliminate the need for steel rebar in concrete construction. By introducing steel fibers to high strength concrete mixture, the overall tensile, compressive and shear strength of the mixture can be improved immensely thus, replacing portions or major parts of the longitudinal, temperature and shrinkage reinforcements. The reduction or elimination of longitudinal and transverse reinforcements in the construction of structural or non-structural members can result in savings in …

Spectroscopic Investigation Of The Chemical And Electronic Properties Of Chalcogenide Materials For Thin-Film Optoelectronic Devices, Kimberly Horsley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials.

For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These …

The Development Of A Laminated Copolyester Electric Guitar, Addison S. Karnes

Electronic Theses and Dissertations

This thesis is an investigation of the fabrication and assembly methodologies employed in the development of a proof-of-principle prototype electric guitar composed of laminated copolyester. The objective of the project was to develop the processes and procedures to create an optimized physical and visual bond between layers to minimize vibratory dissipation, thus maximizing sustain. A high speed CNC router, abrasive waterjet, laser engraver-cutter, as well as various manual fabrication and assembly methods were investigated in the construction of the guitar prototypes. The lamination processes explored include low-temperature, heat-assisted pressure bonding, solvent and chemical welding, and contact adhesives. The project concluded …

Wear Resistant Polydopamine/Ptfe Nanoparticle Composite Coating For Dry Lubrication Applications, Samuel George Beckford

Graduate Theses and Dissertations

This dissertation presents an investigation into the effect of nanoparticle fillers and a polydopamine adhesive primer on the tribological performance of thin PTFE films. The principal objective of this investigation was to reduce wear in PTFE films, an issue which precludes the use of PTFE films in tribological applications requiring high durability. The friction and wear of the composite films were evaluated using a ball-on-flat configuration in linear reciprocating motion. It was found that the use of a polydopamine adhesive primer reduces the wear of PTFE films more than 600 times. X-ray photoelectron spectroscopy (XPS) results show that a tenacious …

Metal Assisted Nanowire Growth For Silicon Nanowire/Amorphous Silicon Composite Solar Cell, Asmaa Ali Sadoon

Graduate Theses and Dissertations

Solar cells are photovoltaic devices that convert the energy of light to electricity by the photovoltaic effect. Crystalline silicon-based solar cells are the most dominant solar cells in the market today due to the high efficiency and relatively low cost. However, the cost of such solar cell is still high due to the large amount of material that is consumed in fabricating such a device. Polycrystalline/amorphous thin films and nanomaterial technologies have emerged to reduce the high cost of c-Si based solar cells and increase the efficiency. In this research, we combined these two technologies to propose and fabricate silicon …

Highly Transparent, Self-Cleaning, And Antireflective Nanoparticle Coatings, Corey Seth Thompson

Graduate Theses and Dissertations

Current solar panel technologies require a sheet of glass to serve as both mechanical support and to protect the cells from the environment. The reflection from the glass sheet can reflect up to 8% of the incident light, reducing the power output of the panel. Antireflective coatings can be used to allow more light to enter the panel to be converted into usable electricity. However, no solid thin film materials exhibit a low enough index of refraction to serve as antireflective coatings for common solar glass. The main goal of this research was to investigate the self-cleaning, antifogging, and antireflective …