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Articles 271 - 300 of 1288

Full-Text Articles in Materials Science and Engineering

Computational Methods To Simulate Molten Salt Thermophysical Properties, Talmage Porter, Michael M. Vaka, Parker Steenblik, Dennis Della Corte Jun 2022

Computational Methods To Simulate Molten Salt Thermophysical Properties, Talmage Porter, Michael M. Vaka, Parker Steenblik, Dennis Della Corte

Faculty Publications

Molten salts are important thermal conductors used in molten salt reactors and solar applications. To use molten salts safely, accurate knowledge of their thermophysical properties is necessary. However, it is experimentally challenging to measure these properties and a comprehensive evaluation of the full chemical space is unfeasible. Computational methods provide an alternative route to access these properties. Here, we summarize the developments in methods over the last 70 years and cluster them into three relevant eras. We review the main advances and limitations of each era and conclude with an optimistic perspective for the next decade, which will likely be …

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Effects Of Release Materials And Temperature Ramp Rates On The Surface Finish Of Carbon-Fiber Composite Components, Sudeep Louis, Thucmy Dang, Ethan Schlocker Jun 2022

Effects Of Release Materials And Temperature Ramp Rates On The Surface Finish Of Carbon-Fiber Composite Components, Sudeep Louis, Thucmy Dang, Ethan Schlocker

Materials Engineering

Toray Advanced Composites is interested in improving their carbon fiber reinforced polymers (CFRP) manufacturing process by enhancing their control on the amount of surface roughness for varied customer preference. Surface roughness of CFRP is important in post-production processes including coating, priming, and painting. This project seeks to determine the effects of three release materials and two temperature ramp rates on the surface finish of CFRP. The release materials used were Tooltech, FEP, and Frekote 770-NC. The two initial temperature ramp rates were 1°F/min and 2°F/min. Surface roughness was measured using a profilometer and analyzed using Ra values. Ra is an …

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Analysis Of Novel Corrosion Resistant Maraging Steels For Use In Additive Manufacturing, Bradley Michael Samuel, James Knowlton Smith Jun 2022

Analysis Of Novel Corrosion Resistant Maraging Steels For Use In Additive Manufacturing, Bradley Michael Samuel, James Knowlton Smith

Materials Engineering

Stainless maraging steel has been proven to be an industry standard material for plastic injection molds. Its high hardness and corrosion resistance extend the lifetime of the tool. This alloy system is also well-suited to additive manufacturing, which can be utilized to form internal cooling channels, further increasing tool life. Using Rapid Alloy Development (RAD) Oerilkon METCO is developing a new composition of stainless maraging tool steel that has high hardness/strength, is corrosion resistant, and has additive-capable melting and solidification properties. This study tests the hardness and corrosion resistance of the new RAD alloys against the current market competitor Corrax …

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Non-Destructive Material Analysis Of Metals And Composites Via Thermography, Jonathan R. Doubt, James L. Chapman Jun 2022

Non-Destructive Material Analysis Of Metals And Composites Via Thermography, Jonathan R. Doubt, James L. Chapman

Materials Engineering

The Naval Surface Warfare Center, Port Hueneme Division, is interested in the development of non-destructive damage assessment of shipboard materials via drones at distance. Long Pulsed Thermography (LPT), a method of non-destructive evaluation, was investigated as a possible method for detecting damage in metals (5005h24 Al alloy and 1008 carbon steel) and composites (aramid fiber honeycomb sandwich structure) at distances from 0.5 m to 3.0 m. LPT was conducted using two 1000 W can lights to heat the samples, and a FLIR E8-XT thermal camera. The images were then analyzed using ImageJ software to determine if damage could be detected …

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Investigation Of The Effects Of Cladding Layers On Longitudinal And Transverse Mechanical Properties In Composite Laminates, Rachel Potratz, Tiffany Foo, Joseph Kamlet Jun 2022

Investigation Of The Effects Of Cladding Layers On Longitudinal And Transverse Mechanical Properties In Composite Laminates, Rachel Potratz, Tiffany Foo, Joseph Kamlet

Materials Engineering

The addition of cladding layers to composite laminates is used in industry to improve bond adhesion and the ease of manufacturing. However, there is no public data on the effects of cladding layers on the mechanical properties of composite components. To directly observe how cladding layers affect mechanical properties, four laminates with zero, one, two, and three cladding layers of twill fabric were added symmetrically to a biased core. The mechanical testing performed was tensile, short beam strength, and compression testing in the longitudinal and transverse directions. The measured strengths were related to the longitudinal properties of the core, and …

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Evaluating The Effects Of Granulated Rubber And Glass Fibers In Polymer Concrete As A Structural Material For Wafer Grinding Machines, Kevin Gabriel Kuehn, Philip Randall Streeter Jun 2022

Evaluating The Effects Of Granulated Rubber And Glass Fibers In Polymer Concrete As A Structural Material For Wafer Grinding Machines, Kevin Gabriel Kuehn, Philip Randall Streeter

Materials Engineering

Polymer concrete is a composite material used to replace cast iron and steel in wafer grinding machines for vibration damping. During the grinding and lapping processes of manufacturing silicon wafers, excessive vibrations may cause subsurface damage which requires additional polishing and reduces yield. Nine compositions containing various levels of granulated rubber and glass fibers were manufactured. CRM WRF-10 granulated rubber was examined at 0%, 5%, and 10% and Corning Cem-Fil glass fibers were added at 0%, 0.5%, and 1% by weight. Smooth-On EpoxAcast 690 epoxy resin was held constant at 16% for each composition. Crushed granite aggregate from Martin Marietta, …

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A Modular Synthesis Of Processable And Thermally Stable Semi-Fluorinated Aryl Ether Polymers Via Step-Growth Polymerization Of Fluoroalkenes, Ketki Eknath Shelar May 2022

A Modular Synthesis Of Processable And Thermally Stable Semi-Fluorinated Aryl Ether Polymers Via Step-Growth Polymerization Of Fluoroalkenes, Ketki Eknath Shelar

Theses and Dissertations

Tailored fluoropolymers remain the leading choice for a wide variety of advanced high-performance applications, including electronic/optical and energy conversion, owing to their unique blend of complementary high-performance properties. Amorphous semi-fluorinated polymers exhibit improved solubility and melt processability when compared to traditional perfluoropolymers. A leading class of semi-fluorinated aryl ether polymers includes perfluorocyclobutyl (PFCB), perfluorocycloalkenyl (PFCA), and fluoroarylene vinylene ether (FAVE) polymers. Monomers containing aromatic trifluorovinyl ethers (TFVE) are used to synthesize PFCB polymers via radical-mediated [2+2] cyclodimerization. On the other hand, FAVE and PFCA polymers are polymerized via base-mediated nucleophilic addition/elimination of bisphenols with TFVE monomers and decafluorocyclohexene respectively. The …

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Challenges And Signal Processing Of High Strain Rate Mechanical Testing, Barae Lamdini May 2022

Challenges And Signal Processing Of High Strain Rate Mechanical Testing, Barae Lamdini

Theses and Dissertations

Dynamic testing provides valuable insight into the behavior of materials undergoing fast deformation. During Split-Hopkinson Pressure Bar testing, stress waves are measured using strain gauges as voltage variations that are usually very small. Therefore, an amplifier is required to amplify the data and analyze it. One of the few available amplifiers designed for this purpose is provided by Vishay Micro-Measurements which limits the user’s options when it comes to research or industry. Among the challenges of implementing the Hopkinson technology in the industry are the size and cost of the amplifier. In this work, we propose a novel design of …

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Biodegradable Active Bio-Nanocomposite Film For The Enhanced Shelf Life Of Tomatoes, Kalpani Y. Perera, Shubham Sharma, Brendan Duffy, Amit K. Jaiswal, Swarna Jaiswal May 2022

Biodegradable Active Bio-Nanocomposite Film For The Enhanced Shelf Life Of Tomatoes, Kalpani Y. Perera, Shubham Sharma, Brendan Duffy, Amit K. Jaiswal, Swarna Jaiswal

Articles

The increased environmental pollution has led to finding sustainable solutions for non-renewable plastic-based food packaging materials. Thus, the use of biomaterial-based packaging material has become an immense trend. This work aims at developing an antimicrobial biodegradable chitosan-alginate bio-nano composite film with TiO2 nanoparticle (NPs) for food packaging applications. The film was developed by a solution casting method. The chemical, mechanical, thermal, barrier, antimicrobial, and biodegradable properties of the packaging films were evaluated. Packaging studies were performed for 15 days for cherry tomatoes. The designed packaging material had enhanced the mechanical properties with a significantly (p < 0.05) higher tensile strength of 15.76 folds and 2 fold higher elongation at break. The UV barrier properties increased by 88.6%, while the film transparency decreased by 87.23%. Molecular interaction of N-H covalent bonds was observed between alginate and chitosan together with TiO2 NPs. The developed bio-nano composite film showed antimicrobial activity against foodborne pathogens E. coli, S. aureus, S. typhi, and L. monocytogene with a log reduction of 7.08, 7.28, 6.04 & 6.02 log CFU/ml respectively at 24 hours incubation period. The film was completely biodegraded and a weight loss of 89.06% was observed in bio-nanocomposite film during the 3 months. Shelf-life estimation of cherry tomato using developed packaging films showed an increase in the shelf-life up to 8 days with stable pH, total soluble solids, and weight with no bacterial growth when packaged with prepared film. Owing to their improved mechanical, UV barrier, antibacterial, and biodegradability, the prepared active bio-nano composite packaging films could be considered a potential candidate for fruit packaging.

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Designing & Building A Microwave Plasma Reactor For Graphene Synthesis, Aviv Zohman, Jerry Larue May 2022

Designing & Building A Microwave Plasma Reactor For Graphene Synthesis, Aviv Zohman, Jerry Larue

Student Scholar Symposium Abstracts and Posters

Graphene’s remarkable electrical, optical, and chemical properties make it a promising successor to indium tin oxide for applications in flexible, transparent electronics. However, efforts to manufacture graphene have been hindered by inefficient synthesis and transfer methods. Chemical vapor deposition (CVD) is commonly used to produce graphene. CVD starts with a blank surface onto which a chemical vapor is deposited to create a single graphene layer. CVD requires extreme temperatures, so only substrates with high melting points are applicable, like metals. This excludes insulative substrates such as polymers which are essential to transparent and flexible devices. Therefore, a subsequent process transfers …

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Characterization Of Hydrogen Embrittlement Sensitivity In High Hardness Steels, David Ahlen Salley May 2022

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 …

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Enhancing Stability Of High-Nickel Cathodes For Lithium-Ion Batteries Through Additive Manufacturing Of Cathode Structure, Matthew Sullivan May 2022

Enhancing Stability Of High-Nickel Cathodes For Lithium-Ion Batteries Through Additive Manufacturing Of Cathode Structure, Matthew Sullivan

Mechanical Engineering Undergraduate Honors Theses

Lithium-ion batteries (LIBs) are currently the best method to store electrical energy for use in portable electronics and electronic vehicles. New cathode materials for LIBs are consistently studied and researched, but few are as promising and attainable as nickel-rich transition metal oxides such as LiNi1-x-yMnxCoyO2 (NMC). NMC materials exist with many different mass ratios, but higher nickel content materials provide higher energy density. With this increase in capacity comes a sacrifice with cyclability, as high-nickel NMC variants are prone to structure collapse, transition metal dissolution, and cracks due to volume change. In this report, mechanical modification of the electrode by …

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Preparation, Cure, And Characterization Of Cyanate Ester-Epoxy Blends, Donald A. Klosterman May 2022

Preparation, Cure, And Characterization Of Cyanate Ester-Epoxy Blends, Donald A. Klosterman

Chemical and Materials Engineering Faculty Publications

Cyanate ester resins are often blended with lower cost epoxy monomers in order to modify the cost, toughness, and processing characteristics. There are also several choices of catalysts that can be used to improve processing, namely by reducing the cure temperature. This study was undertaken to illustrate how a designed experiment approach can be used to systematically investigate a wide range of material combinations and illuminate the basic cure behavior of some simple cyanate ester – epoxy blend combinations. Two commercial cyanate ester resin products were obtained. Each was blended with a bisphenol F based epoxy resin at two different …

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Additive Manufacturing Of Variable Contrast Computed Tomography Anatomical Phantoms Using A Single Feedstock In Fused Filament Fabrication, Cory J. Darling May 2022

Additive Manufacturing Of Variable Contrast Computed Tomography Anatomical Phantoms Using A Single Feedstock In Fused Filament Fabrication, Cory J. Darling

LSU New Orleans Theses and Dissertations

Anatomical phantoms used in biomedical education and training benefit greatly from Fused filament fabrication’s (FFF) ability to rapidly produce complex and unique models. Current materials and methods used in FFF have limited ability to accurately produce phantoms that can mimic the radiological properties of multiple biological tissues. This research demonstrates that the CT contrast of FFF produced models can be modified by varying the concentration of bismuth oxide in acrylonitrile butadiene styrene (ABS) filaments and a tunable CT contrast that mimics the CT contrast ranging from fatty tissue to cortical bone using a single composite filament without introducing artificial image …

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Sustainable Composites From Agricultural And Petroleum Waste, Menisha S. Karunarathna May 2022

Sustainable Composites From Agricultural And Petroleum Waste, Menisha S. Karunarathna

All Dissertations

Green gas emission has been a pervasive and persistent subject of debate for a prolonged period. The soaring number of industries and vehicle fuel emissions presage a concomitant rise in global CO2 emissions. Global cement production is responsible for 8% of the total CO2 release, yet, the production continues due to the surging demand. Hence, there is an ongoing quest to find alternatives for cement and building materials produced with zero to lower CO2 emissions. The work presented in this dissertation focuses on finding recyclable, zero CO2 gas-producing high sulfur biocomposites materials, which can compete with …

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Detection And Identification Of Disturbances By Spectral Analysis Of Structure-Borne Noise During The Production Of A Sealing Seam, Felix Kruppa, Lars Meisenbach, Berend Oberdorfer Dr.-Ing., Bernd Wilke Prof. Dr.-Ing. Apr 2022

Detection And Identification Of Disturbances By Spectral Analysis Of Structure-Borne Noise During The Production Of A Sealing Seam, Felix Kruppa, Lars Meisenbach, Berend Oberdorfer Dr.-Ing., Bernd Wilke Prof. Dr.-Ing.

Journal of Applied Packaging Research

When sealing, disturbances or errors can occur that impair the quality of the sealing seam and, in the worst case, lead to leaks. It is therefore important to identify and eliminate defective packages during production and to minimize the elimination by readjusting machine parameters. The aim of this article is the clear identification of seam quality problems on a vertical forming, filling and sealing machine SVE2520 by evaluating process parameters during the manufacturing process. For this purpose, the structure-borne noise is measured for each seal in order to identify not-usual curves. These not-usual curves are related to different disturbances or …

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Optimizing The Self-Healing Efficiency Of Hydrogel Encapsulated Bacteria In Concrete, Ricardo Hungria Apr 2022

Optimizing The Self-Healing Efficiency Of Hydrogel Encapsulated Bacteria In Concrete, Ricardo Hungria

LSU Master's Theses

Calcium carbonate precipitation through microbial means is a promising pathway for concrete self-healing technologies, mainly for its microcrack sealing attributes. The main goal of this project was to study and optimize the crack healing efficiency of hydrogel encapsulated bacteria in concrete. To achieve this purpose, Bacillus pseudiformus was implemented as the bacteria strain at a concentration of 108 cells/ml. This bacterium strain along with yeast extract was combined along with three different mineral precursors corresponding to magnesium acetate, calcium lactate, and sodium lactate. All these three precursors were evaluated at two concentrations (67.76 mM/l and 75 mM/l). For each …

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Detection Of Trace Heavy Metals In Water: Development Of Electrochemical Sensors, Quang Lam, Joel Mututeke Apr 2022

Detection Of Trace Heavy Metals In Water: Development Of Electrochemical Sensors, Quang Lam, Joel Mututeke

Symposium of Student Scholars

The presence of heavy metals in our ecosystem poses significant ecological and physiological consequences. As a result, numerous techniques are developed for the detection of contaminants in aqueous solutions. However, early and trace detection of such contaminants still remains a challenge. Amongst many techniques, electrochemistry driven sensors have shown promise due to their possibility of miniaturization and low-cost. Our research investigates the use of electrically conducting polymer and atomically thin carbon materials as electrodes towards the development of electrochemical sensor. Nanocomposite electrode films have been synthesized and fabricated using in-situ polymerization technique and the relationship between number of cycles of …

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Zero-Power Ac Current Sensor, Omar Aragonez Apr 2022

Zero-Power Ac Current Sensor, Omar Aragonez

Mechanical Engineering ETDs

In this study, a magnetic piezoelectric cantilever powered AC current and frequency sensor is proposed. This paper covers the configuration of the experimental setup, finite element modeling of the magnetic coupling, and the optimal spatial location of the magnetic proof mass in relation to the wire for smart grid applications. Solid and stranded copper wires of various gauges were used and carried current up to 30A. The magnets act as a proof mass to lower the frequency while also coupling to the magnetic field generated by the current carrying wire. The frequency of the AC current produces a sinusoidal force …

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The Tempering Response Of Cpm® 3v Tool Steel Investigated Through Tensile Testing And Microstructural Observations, Stephen A.C. Hanson Apr 2022

The Tempering Response Of Cpm® 3v Tool Steel Investigated Through Tensile Testing And Microstructural Observations, Stephen A.C. Hanson

Graduate Theses & Non-Theses

Heat treatment, tensile testing failure analysis, and microstructural evaluation of the Crucible Industries tool steel CPM® 3V was undertaken to investigate CPM® 3V’s tempering response for the following samples: As-Hardened (no tempering); tempered at 450°C, 550°C, 650°C, and 700°C; and As-Received (annealed). CPM® 3V tool steel is manufactured by Crucible Industries using their proprietary Crucible Particle Metallurgy (CPM®) technology. This material was heat-treated at four different tempering temperatures and was evaluated for tensile properties according to ASTM E8. A TMS landmark tensile fixture was used to establish the ultimate tensile strength and the yield strength of the material for the …

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Development Of Cost-Effective High-Modulus Asphalt Concrete (Hmac) Mixtures Using Crumb Rubber And Local Construction Materials In Louisiana., Ibrahim A.I.E Elnaml Mar 2022

Development Of Cost-Effective High-Modulus Asphalt Concrete (Hmac) Mixtures Using Crumb Rubber And Local Construction Materials In Louisiana., Ibrahim A.I.E Elnaml

LSU Master's Theses

One of the emerging solutions to enhance the durability of asphalt pavements is the use of a French asphalt mix known as “High-Modulus Asphalt Concrete (HMAC).” This mix uses a hard asphalt binder, high binder content (about 6%), and low air voids content as compared to Superpave mixtures. The key objective of this study was to develop a cost-effective HMAC mixture using crumb rubber and local materials in Louisiana. To achieve this objective, four HMAC mixtures were prepared using two asphalt binders (PG 82-22 and PG 76-22 plus 10% crumb rubber) and two Reclaimed Asphalt Pavement (RAP) contents (20% and …

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Implementation Of Multiscale Mechanisms In Finite Element Analysis Of Active Composite Structures, Amany G. Micheal Prof., Yehia Bahei El Din Prof. Feb 2022

Implementation Of Multiscale Mechanisms In Finite Element Analysis Of Active Composite Structures, Amany G. Micheal Prof., Yehia Bahei El Din Prof.

Centre for Advanced Materials

Composite structures reinforced with electrically active filaments are modeled with the finite element method while the underlying thermo-electromechanical coupling phenomena and damage are taken into consideration. At the outset, structural analysis is performed with a general-purpose finite element code and a special material routine, which propagates local phenomena to the overall scale is utilized. The material routine implements an interactive, multiscale analysis, which provides seamless integration of the mechanics at the composite’s micro, macro, and structural length scales. The interface between the multiscale material routine and the finite element code is made through nonmechanical strains caused by damage, and piezo/pyro-electric …

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Facile One-Step Hydrothermal Method For Nico2s4/Rgo Nanocomposite Synthesis For Efficient Hybrid Supercapacitor Electrodes, Ahmed Mysara, Sayed Y. Attia, Fouad I. El-Hosiny, M A. Sadek, Saad G. Mohamed, M M. Rashad Feb 2022

Facile One-Step Hydrothermal Method For Nico2s4/Rgo Nanocomposite Synthesis For Efficient Hybrid Supercapacitor Electrodes, Ahmed Mysara, Sayed Y. Attia, Fouad I. El-Hosiny, M A. Sadek, Saad G. Mohamed, M M. Rashad

Nanotechnology Research Centre

Spinel nickel-cobalt sulfide (NiCo2S4) supported on reduced graphene oxide (rGO) was fabricated through a facile one-step hydrothermal method for energy storage applications. The distribution of the NiCo2S4 nanoparticles on the rGO surface was found to improve the supercapacitive performance of the assembled device. The NiCo2S4/rGO nanocomposite exhibits outstanding electrochemical behavior with a capacity (C)/specific capacitance (Cs) of 536 C g−1/1072 F g−1 at a current density of 1 A g−1. To further investigate the electrochemical behavior of the NiCo2S4/rGO nanocomposite, a hybrid supercapacitor (HSC) was constructed utilizing a NiCo2S4/rGO positive electrode and an activated carbon …

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Design And Fabrication Of Nanostructured Electrodes For Complementary Electrochemical And Photoelectrochemical Water Splitting, Kholoud El Sayed Abousalem Jan 2022

Design And Fabrication Of Nanostructured Electrodes For Complementary Electrochemical And Photoelectrochemical Water Splitting, Kholoud El Sayed Abousalem

Theses and Dissertations

Designing highly active, durable, and nonprecious electrodes for overall water splitting is of urgent scientific importance to realize sustainable hydrogen production. Accordingly, the need to search efficient energy production systems is of crucial necessity. In this thesis, two various systems for sustainable hydrogen production have been reported using electrochemical and photoelectrochemical pathways. In the first part of the thesis, electrochemical water splitting involving both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has been established. To this end, an innovative approach is demonstrated to synthesize flower-like 3D homogenous trimetallic Mn, Ni, Co phosphide catalysts directly on nickel foam via …

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Materials And Methodologies For Spectroscopic And Optical Analytical Applications In Cultural Heritage Conservation Science, Lyndsay Nichole Kissell Jan 2022

Materials And Methodologies For Spectroscopic And Optical Analytical Applications In Cultural Heritage Conservation Science, Lyndsay Nichole Kissell

Dissertations and Theses

The field of conservation science falls in the intersection of science and art. The work of conservation scientists may include any single subdiscipline of chemistry, though it is most commonly a highly interdisciplinary field taking skills from analytical, organic, and inorganic chemistry, as well as surface and materials science. The aims of conservation scientists are to answer questions about the production and aging of material cultural heritage. Knowing the materials used by an artist can lead to insight about the intentions of the object and knowing how those materials degrade will enable the use of preventative measures to ensure the …

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Implementation Of Multiscale Mechanisms In Finite Element Analysis Of Active Composite Structures, Amany Micheal, Yehia Bahei-El-Din Jan 2022

Implementation Of Multiscale Mechanisms In Finite Element Analysis Of Active Composite Structures, Amany Micheal, Yehia Bahei-El-Din

Centre for Advanced Materials

Interrogation of composite structures for inherent damage is investigated by implementing a three-tier analysis scheme. The analysis starts at the structure level where a general-purpose Finite Element code ABAQUS is employed to obtain the stress field in the second level of analysis which is the composite laminate. A special material routine is prepared to propagate the local fields to the individual plies and hence to the third level of analysis which is the microstructure modeling of the composite. Through the third level of analysis, interface damage between fiber and matrix is checked implementing a certain failure criteria. The interaction between …

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Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian Jan 2022

Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian

Dissertations, Master's Theses and Master's Reports

Composite materials require a multi-scale approach to fully understand its behavior. At the micro level, material behavior analysis is conducted most often using numerical or analytical approaches. These models, however, require validation from experimental data to ensure material predictions are accurate. This study compares a semi-analytical micromechanical analysis tool, MAC/GMC, to experimental results of in-situ microscale transverse compression testing conducted at AFRL facilities. Effective properties, stress-strain curves, stress and strain fields, and damage predictions are compared with experimental outputs. Both generalized method of cells (GMC) and high-fidelity generalized method of cells (HFGMC) theories implemented within MAC/GMC show results that agree …

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A Computational Exploration Of The Scandate Cathode Surface, Shankar Miller-Murthy Jan 2022

A Computational Exploration Of The Scandate Cathode Surface, Shankar Miller-Murthy

Theses and Dissertations--Chemical and Materials Engineering

The exact surface configuration of scandate cathodes has been a point of contention for the materials community for a long time. Without proper understanding of it and the related structures and emission mechanisms, scandate cathodes remain patchy and unreliable emitters. Thus, density functional theory techniques were applied to various potential surface arrangements and found that there are several low-energy surfaces with low work functions that incorporate a scandium interlayer between tungsten and oxygen or otherwise have a scandium-on-tungsten structure. Furthermore, it was discovered that adding a monolayer of scandium directly to a tungsten surface is surprisingly favorable, thermodynamically. While none …

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Pitch-Based Carbon Fiber Derived From Coal Extract Liquids, Cierra Danielle Crowe Jan 2022

Pitch-Based Carbon Fiber Derived From Coal Extract Liquids, Cierra Danielle Crowe

Theses and Dissertations--Chemical and Materials Engineering

Limited coal coking operations and the use of coal-tar pitch as a binding agent in the production of metallurgical anodes has led to a limited availability of coal tar pitch for carbon fiber products. This has sparked interest in utilizing non-metallurgical coal-based liquids as an alternative to traditional coal tar from metcoke operations. This can be achieved by low severity solvent extraction, with heavy aromatic solvents, to produce coal liquids that act as precursor to pitch-based carbon fiber. This thesis aims to establish the processing and determine the impact of utilizing coal liquids to produce carbon fiber. In this work …

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Analysis And Comparison Of Nir Pigments For "Cool" Coating Applications, Karey Steinmetz Jan 2022

Analysis And Comparison Of Nir Pigments For "Cool" Coating Applications, Karey Steinmetz

Williams Honors College, Honors Research Projects

The goal of this research is to compare our own formulation of near infrared radiation (NIR) pigment coating to commercialized ones. These near infrared coatings are designed to be used on roofs of buildings to keep the buildings from absorbing the heat from the sun’s radiation. This would keep the building cooler and use less energy and money to cool the building. In this study, Styrofoam was used to build a lab-scale house and were put under heat lamps that mimicked the sun. Temperatures were taken at three different locations to determine the effectiveness of the pigmented coatings. Color and …

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