Materials Science and Engineering Commons^™

Development Of A Multi-Use Modular Microfluidic Platform Using 3d Printing, Carson Emeigh

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

Microfluidic lab-on-a-chip (LoC) technology has driven numerous innovations due to their ability to perform laboratory-scale experiments on a single chip using microchannels. Although LoC technology has been innovative, it still suffers from limitations related to its fabrication and design flexibility. Typical LoC fabrication, with photolithography, is time consuming, expensive, and inflexible. To overcome the limitations of LoC devices, modular microfluidic platforms have been developed where multiple microfluidic modules, each with a specific function or group of functions, can be combined on a single platform. Modular microfluidics have overcome some of the limitations of LoC devices, but currently, their fabrication is …

Characterization Of Platinum On Carbon Nanoparticles Selectively Coated With Titanium Nitride (Tin), Matthew Maramo

Honors Scholar Theses

Proton exchange membrane fuel cells are a promising low-carbon technology that still face problems including low durability during their normal operation cycles. At the cathode, the carbon supports of the catalysts may corrode. Atomic layer deposition of titanium nitride is performed on prepared catalyst layer samples. The purpose of the deposition is to create a thin film over the carbon supports to reduce carbon support corrosion and improve the lifespan of the fuel cell. Sheet resistances and contact angles are measured for the samples before and after the deposition, although some samples did not receive the deposition and post-deposition characterization …

The Effect Of Extended Saltwater Absorption And Uv Cure On The Compressive Properties Of Msla 3d-Printed Photopolymer Resin Samples With Printing Variations, Suzanne Dixon

Theses and Dissertations

Liquid Crystal Display (LCD) 3D printers, also known as Masked Stereolithography Apparatus (MSLA), is a type of vat polymerization printing technique that cures liquid resin into a solid object. This technique is relatively new. Consequently, there is a shortage of detailed research on the impact of long-term environmental exposure on the MSLA-printed materials. The research within this document informs engineers and scientists of resin compressive properties after extended exposure to saltwater and ultraviolet (UV) light. Saltwater absorption of the material was analyzed at atmospheric pressure, 30-psi, 60-psi, and 90-psi; the samples reached saturation in saltwater after 56 days. The variation …

Thermal Conductivity Of Thin Porous Ceramic Coatings: An Analytical And Experimental Study, Lei Zhao

Theses and Dissertations

An analytical model of the thermal conductivity of the porous yttrium-stabilized zirconia (YSZ) layer used in the thermal barrier coatings (TBCs) is presented. Such high-temperature resistant coatings are essential to protect the metallic components of gas turbine engines. The model calculates the conductivity based on the coating's porosity, pore size distribution, and pore morphology, including the individual pore cross-section area, aspect ratio, and orientation, which are extracted from the scanning electron microscopy images. The model was verified through comparisons with numerical simulation results from a multiphysics software tool. A laser temperature gradient test was performed to validate the analytical model …

A Comprehensive Investigation Of The Influence Of Geometric Structure On The Shape Memory Performance Of Nafion, Jade Thomas

Mechanical Engineering Undergraduate Honors Theses

While perfluorosulfonic acid (PFSA) membranes have primarily been used in fuel cells due to their chemical, thermal, and mechanical stability, one PFSA, Nafion, boasts two unique characteristics: a broad glass transition (~55 °C to 130 °C) and a temperature-persistent electrostatic network. The combination of these two characteristics endows Nafion with exceptional shape memory properties – the ability of a material to morph and transform into pre-programmed shapes when exposed to an external stimulus – with enhanced permanent shape memorization, and a potentially near-infinite number of temporary shape memorization. This study focused on expanding the base of knowledge surrounding Nafion’s shape …

Boron-Doped Diamond As A Resilient Electrode Material In Molten Salts, Hannah Katherine Patenaude

UNLV Theses, Dissertations, Professional Papers, and Capstones

Molten salt chemistry has a range of applications within nuclear technology, including for the Molten Salt Reactors (MSRs) and pyroprocessing to recover valuable actinides for energy and national security needs. However, the high-temperature, corrosive nature of molten salts makes them particularly challenging to deploy on an industrial scale and study in benchtop measurements. Material accountability and corrosion monitoring of MSR fuels are essential components to the successful deployment of MSRs, and electroanalytical techniques like cyclic voltammetry (CV) and spectroelectrochemistry (SEC) can provide a wealth of information to describe salt systems in situ. To perform such measurements, it is imperative to …

Germanium-Tin On Silicon For Integrated Photonics And Integrated Quantum Materials, Shang Liu

Dartmouth College Ph.D Dissertations

Group IV GeSn alloys are attracting attention due to their compatibility with the complementary metal-oxide-semiconductor (CMOS) process. On one hand, Ge-rich GeSn alloys with a tunable direct bandgap are well-suited to infrared (IR) photonic applications such as image sensors. On the other hand, Sn-rich GeSn alloys in diamond cubic α phase are topological quantum materials (TQM) holding potential for important quantum applications. However, directly growing GeSn on Si remains challenging due to the lattice mismatch. Regular epitaxial GeSn grown on a Ge buffer layer is not applicable to many photonic applications including CMOS image sensors (CIS) because the buffer layer …

Synthesis Of Bimetallic Nickel And Cobalt Phosphide Nanostructures For Electrocatalysis, Sarah Meixin York

Graduate Theses and Dissertations

Transition metal phosphides have become a new class of materials to be considered as promising catalysts for a number of applications including electrochemical hydrogen evolution (HER). Electrocatalysis in hydrogen evolution is a heavily studied field due to the increasing desire to develop more efficient and more cost-effective catalysts for clean hydrogen production. This project develops a chemical approach to synthesizing bimetallic cobalt-nickel phosphide nanostructures for their use in HER. The synthesis is accomplished by thermal decomposition of the metal precursors in the presence of carbon monoxide (CO) and trioctyl phosphine (TOP). The resulting nanostructures were characterized using transition electron microscopy …

Adipose Stem Cell Response To Borophosphate Bioactive Glass, Nada A. Abokefa, Bradley A. Bromet, Rebekah L. Blatt, Makenna S. Pickett, Richard K. Brow, Julie A. Semon

Materials Science and Engineering Faculty Research & Creative Works

Silicate and Borate Bioactive Glasses Have Been Reported to Create Alkaline Conditions by Rapidly Releasing Ions When Reacting in Aqueous Solution. at Certain Levels, This Alkaline Solution Can Negatively Affect Cell Viability. Adding Phosphate Ions to the Glass Composition Can Control the Degradation Rate of Bioactive Glasses and Create a Neutral PH Environment. This Study Evaluated a Series of Boro phosphate Bioactive Glasses (BPBGs) with Nominal Molar Compositions 16Na₂O_-24CaO-XB₂O₃-(60-X) P₂O₅, Where X = 0, 40, or 60. the Phosphate (X0) Glass (PBG) Produced an Acidic Solution When Dissolved …

Green Chemistry Design Of Epoxies From Biomass For Circular Economy, Kavya Ganesan

All Dissertations

The commercial epoxies market in automobiles has been growing mainly in terms of usage as automotive coatings and lightweight composite structures manufacturing. Most of these commercial epoxies are bisphenol-based. Bisphenol-based epoxies are a class of high-performance polymer materials that, when cured, yield thermosets with high mechanical, thermal and chemical resistance properties. Roughly, North America produces around 123 billion pounds of these epoxies which are used in various industrial applications like coatings, composites, structural parts, automotive, electronics, construction etc. These epoxies are mainly manufactured from bisphenol-A (BPA) and epichlorohydrin (EPH). These raw materials are sourced from fossil fuel resources and are …

Numerical Simulation Of Laser Induced Elastic Waves In Response To Short And Ultrashort Laser Pulses., Alireza Zarei

All Dissertations

In an era of intensified market competition, the demand for cost-effective, high-quality, high-performance, and reliable products continues to rise. Meeting this demand necessitates the mass production of premium products through the integration of cutting-edge technologies and advanced materials while ensuring their integrity and safety. In this context, Nondestructive Testing (NDT) techniques emerge as indispensable tools for guaranteeing the integrity, reliability, and safety of products across diverse industries.

Various NDT techniques, including ultrasonic testing, computed tomography, thermography, and acoustic emissions, have long served as cornerstones for inspecting materials and structures. Among these, ultrasonic testing stands out as the most prevalent method, …

Design And Optimization Of A Novel Monolithic Spring For High-Frequency Press-Pack Sic Fet Modules, Bogac Canbaz

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

Silicon Carbide (SiC) Field-Effect Transistor (FET) modules lead the way in power electronics, being superior in efficiency and robustness for high-frequency applications. The shift towards SiC from traditional silicon (Si)-based devices is driven by its superior thermal conductivity, higher electric field strength, and operational efficiency at elevated temperatures. These features are critical for the development of next-generation, grid-oriented power converters aimed at enhancing the reliability and sustainability of power systems. This research focuses on high-frequency press-pack (HFPP) SiC FET modules, addressing the primary challenge of miniaturizing SiC FET dies without compromising performance, through an innovative press-contact design essential for increased …

Smart Manufacturing Of Cement: From Lab-Scale Simulation And Testing To Industry-Scale Deployment., Juan David Tabares Tamayo

Electronic Theses and Dissertations

Cement kilns are controlled by experienced process operators who follow experience-based industry guidelines using data collected and fundamental knowledge. The manufacturing process, which is equipped with sensors and equipment, transfers data/information to the operators to aid standardized decision-making operations. In contrast, companies have used such data to develop and implement digital solutions for predictive control systems; in effect, FLSmidth and Rockwell Automation. However, despite the availability of automated control systems and investigation in automation for process monitoring and optimization, opportunities to radically optimize cement manufacturing are still abundant and in need of implementation. Therefore, this research developed simulation models and …

Drag Reduction In Channel Flow Configurations For Laminar And Turbulent Flow Past Superhydrophobic Surfaces, Henry Louis Ems

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

In this work, we present friction drag reduction in minichannel laminar flow past superhydrophobic metallic surfaces. Femtosecond laser surface processing (FLSP), a one-step scalable method, was used to create permanent microscale and nanoscale structures on 316 stainless steel plates. The resulting superhydrophilic plates were covered by tall (215 μm) or short (27 μm) structures. The FLSP plates were then transitioned to superhydrophobic by evaporative deposition of a fluorinated silane, a low surface energy coating. Using purified water, the friction factor was obtained by measuring pressure drop along a minichannel with a rectangular cross section for flow rates corresponding …

The Analysis Of Mechanical Exfoliation Of Graphene For Various Fabrication And Automation Techniques, Lance Yarbrough

Mechanical Engineering Undergraduate Honors Theses

Mechanical Exfoliation of Graphene is an often-overlooked portion of the fabrication of quantum devices, and to create more devices quickly, optimizing this process to generate better flakes is critical. In addition, it would be valuable to simulate test pulls quickly, to gain insight on flake quality of various materials and exfoliation conditions. Physical pulls of graphene at various temperatures, pull forces, and pull repetitions were analyzed and compared to the results of ANSYS simulations, solved for similar results. Using ANSYS’ ability to predict trends in exfoliations, flake thickness and coverage using stress and deflection analyses were investigated. Generally, both strongly …

Effects Of Ferrite And Graphite Phases On Scratch Characteristics Of Nodular Cast Iron, Zhitong Xu, Ming Liu, Chenghui Gao, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

In this work, we conduct micro-scratch tests of nodular cast iron with Vickers indenter under constant normal load and investigate the effects of individual phases (i.e., ferrite and graphite phases) on the scratch charac- teristics of nodular cast iron. Using a bimodal Gaussian model to fit the experimental data of penetration depth, residual depth, elastic recovery rate, and scratch hardness, we calculate the contribution percentages of indi- vidual phases to scratch variables. The scratch variables are independent of the scratch speed used in this work, while the penetration depth increases linearly with increasing the normal load. There exists a large …

A Mechanical Model For Stress Relaxation Of Polylactic Acid/Thermoplastic Polyurethane Blends, Yi-Sheng Jhao, Hao Ouyang, Chien-Chao Huang, Fuqian Yang, Sanboh Lee

Chemical and Materials Engineering Faculty Publications

Polylactic acid (PLA) is considered a promising biodegradable polymer alternative. Due to its high brittleness, composite materials made by melt blending thermoplastic polyurethane (TPU) with PLA can enhance the toughness of PLA. To understand the forced aging caused by stress relaxation in polymer materials, this study explains the stress relaxation experiments of PLA/TPU blends with different mass ratios under applied strain through mechanical model simulations. The Kelvin representation of the standard linear solid model (SLSM) is used to analyze the stress relaxation data of TPU/PLA blends, successfully explaining that the Young’s moduli (E1 and E2) of springs decrease with increasing …

The Epitaxial Growth Of Ge And Gesn Semiconductor Thin Films On C-Plane Sapphire, Emmanuel Wangila, Calbi Gunder, Petro M. Lytvyn, Mohammad Zamani-Alavijeh, Fernando Maia De Oliveira, Serhii Kryvyi, Hryhorii Stanchu, Aida Sheibani, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo

Physics Faculty Publications and Presentations

Ge_1−xSn_x growth on a new sapphire platform has been demonstrated. This involved the growth of GeSn on Ge/GaAs layers using the algorithm developed. The resultant growths of Ge on GaAs/AlAs/sapphire and Ge_1−xSn_x on Ge/GaAs/AlAs/sapphire were investigated by in situ and ex situ characterization techniques to ascertain the surface morphology, crystal structure, and quality. The growth mode of Ge on GaAs was predominantly two-dimensional (2D), which signifies a layer-by-layer deposition, contributing to enhanced crystal quality in the Ge/GaAs system. The growth of Ge_1−xSn_x with 10% Sn on a graded profile for 30 …

Revealing The Three-Dimensional Arrangement Of Polar Topology In Nanoparticles, Chaewa Jeong, Juhyeok Lee, Hyesung Jo, Jaewhan Oh, Hionsuck Baik, Kyoung-June Go, Junwoo Son, Si-Young Choi, Sergey Prosandeev, Laurent Bellaiche, Yongsoo Yang

Physics Faculty Publications and Presentations

In the early 2000s, low dimensional ferroelectric systems were predicted to have topologically nontrivial polar structures, such as vortices or skyrmions, depending on mechanical or electrical boundary conditions. A few variants of these structures have been experimentally observed in thin film model systems, where they are engineered by balancing electrostatic charge and elastic distortion energies. However, the measurement and classification of topological textures for general ferroelectric nanostructures have remained elusive, as it requires mapping the local polarization at the atomic scale in three dimensions. Here we unveil topological polar structures in ferroelectric BaTiO₃ nanoparticles via atomic electron tomography, which …

Development, 3d Printing, And Sintering Of Aluminum-Magnesium Alloy Pastes For In-Space Manufacturing Applications, Fatou Ndiaye

Electronic Theses and Dissertations

This study explores the additive manufacturing process of paste printing, sintering, and de-binding for fabricating aluminum-magnesium alloy components. The paste formulation involved combining aluminum powder with varying magnesium concentrations, utilizing acrylic polyol, solvent, and plasticizer to create a homogeneous mixture. Printing parameters were optimized to ensure continuous pressure for improved extrusion. Sintering conditions involved incremental temperature increases with nitrogen flow to remove solvents. Density measurements, tensile tests, and shrinkage calculations were conducted to assess part quality post-sintering. The study revealed significant improvements in part quality with 5 wt.% magnesium incorporation within aluminum, although density and tensile strength fell short of …

Investigation Of Domain Formation During Phase Separation In A Mixture Of Flexible And Rigid Biopolymers, Steven Huntley

All Theses

Complex fluids and heterogenous mixtures composed of multiple types of polymers are found throughout industrial and biological fluid systems. For example, extrusion based additive manufacturing systems pass dense mixtures of polymers through the extrusion heads to deposit composite polymeric materials. In cells, active and complex mixtures of biopolymers self-organize into assemblies that perform critical physiological functions.

Polymers in dense solutions undergo phase separation as a result of differences in physiochemical properties. A few examples of these properties include charge, structure, rigidity, and hydrophobicity. We observe the formation of polymer domains composed of rigid and a flexible biopolymer species that phase …

Layered Structure Protonic Ceramic Conductors Of The Form Ba5in2+Xal2zr1-Xo13-Δ, Nathan Cretegny

All Theses

In this work, the hexagonal perovskite of targeted composition Ba₅In_2+xAl₂Zr_1-xO₁₃ (x=0, 0.1, 0.2) was synthesized via a solid-state synthesis route to study the impact of oxygen vacancy concentration in layered hexagonal perovskites. Precursor oxides were mixed in stoichiometric proportions, calcined between 800-1200℃ and sintered at 1475℃. The sintered pellets were crushed into fine powders to investigate the chemistry and structure through X-ray diffraction, neutron diffraction, inductively coupled plasma mass spectrometry, and nuclear magnetic resonance. Dense pellets were used to study conductivity properties using electrochemical impedance spectroscopy.

The synthesis approach produced 100% …

Improved Ballistic Impact Resistance Of Nanofibrillar Cellulose Films With Discontinuous Fibrous Bouligand Architecture, Colby Caviness

All Theses

Natural protective materials offer unparalleled solutions for impact-resistant material designs that are simultaneously lightweight, strong, and tough. Particularly, the dactyl club of mantis shrimp features chitin nanofibrils organized in a Bouligand structure, which has been shown to effectively dissipate high-impact energy during powerful strikes. The mollusk shells also achieve excellent mechanical strength, toughness, and impact resistance with a staggered, layer-by-layer structure. Previous studies have shown that hybrid designs, by combining different bioinspired microstructures, can lead to enhanced mechanical strength and energy dissipation capabilities. Nevertheless, it remains unknown whether combining Bouligand and staggered structures in nanofibrillar cellulose (NFC) films, forming a …

Stabilization Of Layered Transition Metal Oxide Positive Electrodes At High Potential For Sodium Ion Batteries, Eric Gabriel

Boise State University Theses and Dissertations

As global demand for energy storage rises in response to the proliferation of electric vehicles and intermittent renewable energy sources, the resources associated with popular energy storage systems are increasingly strained. Lithium ion batteries (LIBs) rely heavily on elements with low abundance and unstable supply chains, while sodium ion batteries (SIBs) are a promising alternative technology based on abundant, globally available elements such as iron and sodium. However, the electrochemical performance of SIBs must be improved to enable their commercial viability. In the class of layered transition metal oxide (LTMOs) materials that are strong candidates as positive electrode materials for …

Engineering Multifunctional Silicon Nanostructures From Biorenewable Cellulose Nanocrystals, Nancy Chen

All Dissertations

The imperative search for alternative materials to address the pressing demand for advance energy storage is underscored by the escalating environmental predicaments. Lithium-ion batteries (LIBs) with graphite anodes have become the benchmark in energy storage; however, they are approaching a saturation point in terms of energy density. Silicon emerges as a promising contender to supplant graphite, owing to its profuse availability, cost-effectiveness, and impressive specific capacity of 4200 mAh g^-1. By integrating silicon anodes, LIBs stand to undergo a radical transformation, markedly diminishing in weight and size, thus heralding a novel wave of compact, lightweight energy storage systems. …

Process-Structure-Property-Performance Modeling For Semicrystalline Thermoplastics And Composites, Tatiana Stepanova

All Dissertations

With a growing focus on reducing the adverse effects of transportation on the environment, industries are seeking fuel-efficient and sustainable solutions. Fuel efficiency can be improved in several ways, but structural lightweighting has demonstrated overall effectiveness. In this regard, thermoplastic composites and additive manufacturing (AM) thermoplastics have become viable candidates for use in the automotive industry, given the need for weight reduction and efficiency improvement.

The advantages of AM include simplifying supply chains, simplifying part geometry, and enabling mass customization. In order to design high-performance AM structures, extensive modeling and simulation are required. AM thermoplastics are similar to conventional manufacturing …

A Manufacturing-To-Response Pathway For Manufacturing Optimization Of Carbon Fiber Reinforced Polymer Composite Structures, Madhura Limaye

All Dissertations

Over the past decade, there has been an increased adoption of thermoplastic and thermoset based continuous carbon fiber reinforced polymer (CFRP) composites for structural applications in several industries. Among the different manufacturing methods, thermoforming process for thermoplastic based continuous CFRP’s offer a major advantage in reducing cycle times for large scale productions. Similarly, out-of-autoclave curing process for thermoset based continuous CFRP’s using heated tooling enables production of large composite structures. However, these manufacturing processes can have a significant impact on the structural performance of parts by inducing undesirable effects. These effects include inhomogeneous fiber orientations, thickness variations, and residual stresses …

Additive Manufacturing With Bioresorbable Polymers: Process-Structure-Property Relationships For Biomimetic Tissue Scaffolds, Clayton Joseph Culbreath

All Dissertations

Tissue engineering has a base requirement of scaffold structures to support cell growth, proliferation, and regeneration. However, attempts to use artificial scaffold structures have often fallen short of clinical needs to justify the change away from the established, biologic-based current standard of care. Based on the limited number of successful tissue scaffolds produced by material extrusion modes of additive manufacturing, fused filament 3d printing and electrospinning, critical design specifications for a tissue scaffold are six minimum requirements: 1) biocompatibility, 2) porosity, 3) mechanical properties, 4) bioresorbable medical grade materials, 5) bioactivity, and 6) appropriately scaled production methods compliant with medical …

Machine Learning Assisted Discovery Of High-Performance Perovskites For Hydrogen Production, Ximei Zhai

All Dissertations

Hydrogen has significantly contributed to the global energy transition as a clean energy carrier. However, traditional hydrogen production involves energy-intensive processes with heavy carbon emissions. High-temperature water splitting to generate hydrogen has become a promising route for clean hydrogen production. Directly utilizing concentrated solar heat to perform solar thermochemical hydrogen (STCH) production is considered one of the most eco-friendly hydrogen production options. At the same time, high-temperature electrolysis in protonic ceramic electrolysis cells (PCECs) can efficiently utilize intermittent and cost-effective renewable electricity to produce hydrogen. Perovskite oxides with good redox capability and tolerance for oxygen deficiency are considered the most …

Volatile Crystalline Semiconductor Core Fibers, Thomasina Zaengle

All Dissertations

Optical fibers play critical roles across many facets of everyday life from communications to e-commerce to sensing and security. The ubiquity of optical fibers arises from their intrinsic clarity and, as glasses, their ability to be thermally drawn at high speeds over long distances when suitably heated about their glass transition temperature. Sixteen years ago, the first thermally drawn crystalline core fibers were fabricated using the molten core method, whereby a melt is confined within a glass capillary tube that is then drawn to fiber. This opened the door to crystalline semiconductor core fibers, which are now the backbone of …