Materials Science and Engineering Commons^™

Understanding The Structure-Property-Performance Relationship Of Silicon Negative Electrodes, Jiazhi Hu

Theses and Dissertations--Chemical and Materials Engineering

Rechargeable lithium ion batteries (LIBs) have long been used to power not only portable devices, e.g., mobile phones and laptops, but also large scale systems, e.g., electrical grid and electric vehicles. To meet the ever increasing demand for renewable energy storage, tremendous efforts have been devoted to improving the energy/power density of LIBs. Known for its high theoretical capacity (4200 mAh/g), silicon has been considered as one of the most promising negative electrode materials for high-energy-density LIBs. However, diffusion-induced stresses can cause fracture and, consequently, rapid degradation in the electrochemical performance of Si-based negative electrodes. To mitigate the detrimental effects …

Lignin-Derived Carbon And Nanocomposite Materials For Energy Storage Applications, Wenqi Li

Theses and Dissertations--Biosystems and Agricultural Engineering

With a growing demand for electrical energy storage materials, lignin-derived carbon materials have received increasing attention in recent years. As a highly abundant renewable carbon source, lignin can be converted to a variety of advanced carbon materials with tailorable chemical, structural, mechanical and electrochemical properties through thermochemical conversion (e.g. pyrolysis). However, the non-uniformity in lignin structure, composition, inter-unit linkages and reactivity of diverse lignin sources greatly influence lignin fractionation from plant biomass, the pyrolysis chemistry, and property of the resulting carbon materials.

To introduce a better use of lignocellulosic biomass to biofuels and co-products, it is necessary to find novel …

Enhanced Surface Integrity With Thermally Stable Residual Stress Fields And Nanostructures In Cryogenic Processing Of Titanium Alloy Ti-6al-4v, James R. Caudill

Theses and Dissertations--Mechanical and Aerospace Engineering

Burnishing is a chipless finishing process used to improve surface integrity by severe plastic deformation (SPD) of surface asperities. As surface integrity in large measure defines the functional performance and fatigue life of aerospace alloys, burnishing is thus a means of increasing the fatigue life of critical components, such as turbine and compressor blades in gas turbine engines. Therefore, the primary objective of this dissertation is to characterize the burnishing-induced surface integrity of Ti-6Al-4V alloy in terms of the implemented processing parameters. As the impact of cooling mechanisms on surface integrity from SPD processing is largely unexplored, a particular emphasis …

Design And Process Of 3d-Printed Parts Using Composite Theory, Jordan Garcia

Theses and Dissertations--Mechanical and Aerospace Engineering

3D printing is a revolutionary manufacturing method that allows the productions of engineering parts almost directly from modeling software on a computer. With 3D printing technology, future manufacturing could become vastly efficient. However, it is observed that the procedures used in 3D printing differ substantially among the printers and from those used in conventional manufacturing. In this thesis, the mechanical properties of engineering products fabricated by 3D printing were comprehensively evaluated and then compared with those made by conventional manufacturing. Three open-source 3D printers, i.e., the Flash Forge Dreamer, the Tevo Tornado, and the Prusa, were used to fabricate the …

The Study Of Scandate Cathode And Its Characterization Under Various Stages Of Processing, Xiaomeng Zhang

Theses and Dissertations--Chemical and Materials Engineering

Scandate cathode under various processing stages: scandia nano-powder, tungsten scandia mix powder, sintered and impregnated pellets, were characterized with techniques that included electron microscopy, EDS, XPS, and work function measurements. The size and shape uniformity of nano-scale scandia particles changed from round to square and polyhedron during heat treatment. Reduction in size and improvement in size uniformity as heat treating temperature increased were observed. When determining the highest Sc coverage, three assessment methods were used and with their combined results, it was concluded that set VII had the highest Sc at%. In the sintered pellets, it was observed with SEM …

Biomass-Derived Activated Carbons For Electrical Double Layer Supercapacitors: Performance And Stress Effect, Wenxin Cao

Theses and Dissertations--Chemical and Materials Engineering

The vigorous development of human civilization has significantly increased the energy consumption in recent years. There is a great need to use renewable energy sources to substitute the depleting traditional fossil fuels, such as crude oil, natural gas and coal. The development of low-cost and high-performance energy storage devices (ESDs) and systems have drawn great attention due to their feasibility as backup power supply and their applications in portable electronics and electric vehicles. Supercapacitors are among the most important ESDs because of their long charging-discharging cycle life, high power capability and a large operating temperature range. In this thesis, high-performance …

Mechanical Properties And Degradation Of High Capacity Battery Electrodes: Fundamental Understanding And Coping Strategies, Yikai Wang

Theses and Dissertations--Chemical and Materials Engineering

Rechargeable lithium ion and lithium (Li) metal batteries with high energy density and stability are in high demand for the development of electric vehicles and smart grids. Intensive efforts have been devoted to developing high capacity battery electrodes. However, the known high capacity electrode materials experience fast capacity fading and have limited cycle life due to electromechanical degradations, such as fracture of Si-based electrodes and dendrite growth in Li metal electrodes. A fundamental understanding of electromechanical degradation mechanisms of high capacity electrodes will provide insights into strategies for improving their electrochemical performance. Thus, this dissertation focuses on mechanical properties, microstructure …

Nanoharvesting And Delivery Of Bioactive Materials Using Engineered Silica Nanoparticles, Md Arif Khan

Theses and Dissertations--Chemical and Materials Engineering

Mesoporous silica nanoparticles (MSNPs) possess large surface areas and ample pore space that can be readily modified with specific functional groups for targeted binding of bioactive materials to be transported through cellular barriers. Engineered silica nanoparticles (ESNP) have been used extensively to deliver bio-active materials to target intracellular sites, including as non-viral vectors for nucleic acid (DNA/RNA) delivery such as for siRNA induced interference. The reverse process guided by the same principles is called “nanoharvesting”, where valuable biomolecules are carried out and separated from living and functioning organisms using nano-carriers. This dissertation focuses on ESNP design principles for both applications. …

The Fabrication And Characterization Of Metal Oxide Nanoparticles Employed In Environmental Toxicity And Polymeric Nanocomposite Applications, Matthew Logan Hancock

Theses and Dissertations--Chemical and Materials Engineering

Ceria (cerium oxide) nanomaterials, or nanoceria, have commercial catalysis and energy storage applications. The cerium atoms on the surface of nanoceria can store or release oxygen, cycling between Ce³⁺ and Ce⁴⁺, and can therefore act as a therapeutic to relieve oxidative stress within living systems. Nanoceria dissolution is present in acidic environments in vivo. In order to accurately define the fate of nanoceria in vivo, nanoceria dissolution or stabilization is observed in vitro using acidic aqueous environments.

Nanoceria stabilization is a known problem even during its synthesis; in fact, a carboxylic acid, citric acid, is …

Scanning Probe Microscopy Measurements On 2d Materials And Iridates, Armin Ansary

Theses and Dissertations--Physics and Astronomy

In the past two decades, there has been a quest to understand and utilize novel materials such as iridates and two-dimensional (2D) materials. These classes of materials show a lot of interesting properties both in theoretical predictions as well as experimental results. Physical properties of some of these materials have been investigated using scanning probe measurements, along with other techniques.

One-dimensional (1D) catalytic etching was investigated in few-layer hexagonal boron nitride (hBN) films. Etching of hBN was shown to share several similarities with that of graphitic films. As in graphitic films, etch tracks in hBN commenced at film edges and …

Lightweight Thermal Management Material For Enhancement Of Through-Thickness Thermal Conductivity, Matthew Collins Weisenberger

Center for Applied Energy Research Faculty Patents

A flexible sheet of aligned carbon nanotubes includes an array of aligned nanotubes held in a polymer matrix material. The carbon nanotubes have an average length of between about 50 microns and about 500 microns. The polymer matrix has an average thickness of between about 10 microns and about 500 microns. The flexible sheet has a density of about 0.2 to about 1.0 glee and includes between about 98 to about 60 weight percent aligned carbon nanotubes and between about 2 and about 40 weight percent polymer. A tape of aligned carbon nanotubes, a method for producing a tape of …

Determination Of Chemical Speciation Of Arsenic And Selenium In High-As Coal Combustion Ash By X-Ray Photoelectron Spectroscopy: Examples From A Kentucky Stoker Ash, Biao Fu, James C. Hower, Shifeng Dai, Sarah M. Mardon, Guijian Liu

Center for Applied Energy Research Faculty and Staff Publications

Knowledge of the chemical speciation of arsenic and selenium in coal fly ash is essential in the evaluation of the environmental behavior of fly ash disposed in a landfill in a natural environment. In this study, a series of high-As coal fly ash from stoker boilers were collected to determine the chemical forms of arsenic and selenium. The ash surface chemical characteristics and the speciation of arsenic and selenium were characterized by X-ray photoelectron spectroscopy and X-ray-induced Auger electron spectroscopy. The results indicate that the surface enrichment ratio for selenium (63.3–309.5) is higher than that of arsenic (1.2–21.2). The Wagner …

A Simple And Robust Approach To Reducing Contact Resistance In Organic Transistors, Zachary A. Lamport, Katrina J. Barth, Hyunsu Lee, Eliot Gann, Sebastian Engmann, Hu Chen, Martin Guthold, Iain Mcculloch, John E. Anthony, Lee J. Richter, Dean M. Delongchamp, Oana D. Jurchescu

Chemistry Faculty Publications

Efficient injection of charge carriers from the contacts into the semiconductor layer is crucial for achieving high-performance organic devices. The potential drop necessary to accomplish this process yields a resistance associated with the contacts, namely the contact resistance. A large contact resistance can limit the operation of devices and even lead to inaccuracies in the extraction of the device parameters. Here, we demonstrate a simple and efficient strategy for reducing the contact resistance in organic thin-film transistors by more than an order of magnitude by creating high work function domains at the surface of the injecting electrodes to promote channels …

Concentrically Loaded Circular Rc Columns Partially Confined With Frp, Sahar Y. Ghanem, Issam E. Harik

Civil Engineering Faculty Publications

Wrapping reinforced concrete (RC) columns with fiber reinforced polymer (FRP) composites is effective in increasing their capacity. The current state of the art concentrates primarily on fully wrapped columns and few studies dealt with partially wrapped ones. The objective herein is to evaluate the effectiveness of partial wraps (or strips) and to develop a confined concrete compressive stress–strain (f_c − ε_c) model that accounts for partial wrapping. Three-dimensional finite element (FE) models are generated to evaluate the influence of different parameters on the behavior of concentrically loaded RC circular columns that are partially and fully wrapped …

Determining The Degree Of [001] Preferred Growth Of Ni(Oh)2 Nanoplates, Taotao Li, Ning Dang, Wanggang Zhang, Wei Liang, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Determining the degree of preferred growth of low-dimensional materials is of practical importance for the improvement of the synthesis methods and applications of low-dimensional materials. In this work, three different methods are used to analyze the degree of preferred growth of the Ni(OH)₂ nanoplates synthesized without the use of a complex anion. The results suggest that the preferred growth degree of the Ni(OH)₂ nanoplates calculated by the March parameter and the expression given by Zolotoyabko, which are based on the analysis and texture refinement of the X-ray diffraction pattern, are in good accordance with the results measured by …

Cellulose-Specific Type B Carbohydrate Binding Modules: Understanding Oligomeric And Non-Crystalline Substrate Recognition Mechanisms, Abhishek A. Kognole, Christina M. Payne

Chemical and Materials Engineering Faculty Publications

Background: Effective enzymatic degradation of crystalline polysaccharides requires a synergistic cocktail of hydrolytic enzymes tailored to the wide-ranging degree of substrate crystallinity. To accomplish this type of targeted carbohydrate recognition, nature produces multi-modular enzymes, having at least one catalytic domain appended to one or more carbohydrate binding modules (CBMs). The Type B CBM categorization encompasses several families (i.e., protein folds) of CBMs that are generally thought to selectively bind oligomeric polysaccharides; however, a subset of cellulose-specific CBM families (17 and 28) appear to bind non-crystalline cellulose more tightly than oligomers and in a manner that discriminates between surface topology.

Results: …

Water Processable N-Type Organic Semiconductor, Ruben S. Riquelme, Matthew Collins Weisenberger, Camila F. Gomez

Center for Applied Energy Research Faculty Patents

The present invention concerns a water-processable n-type semiconductor comprised of polyvinylpyrrolidone (PVP), carbon nanotubes (CNTs) and poly(ethyleneimine) (PEI). The semiconductors are prepared by providing PVP and CNTs in a hydrophilic slurry and dispersing therein small amounts of PEI.

Linking Lignin Source With Structural And Electrochemical Properties Of Lignin-Derived Carbon Materials, Wenqi Li, Yan Zhang, Lalitendu Das, Yikai Wang, Mi Li, Namal Wanninayake, Yunqiao Pu, Doo Young Kim, Yang-Tse Cheng, Arthur J. Ragauskas, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Valorization of lignin to high-value chemicals and products along with biofuel production is generally acknowledged as a technology platform that could significantly improve the economic viability of biorefinery operations. With a growing demand for electrical energy storage materials, lignin-derived activated carbon (AC) materials have received increasing attention in recent years. However, there is an apparent gap in our understanding of the impact of the lignin precursors (i.e., lignin structure, composition and inter-unit linkages) on the structural and electrochemical properties of the derived ACs. In the present study, lignin-derived ACs were prepared under identical conditions from two different lignin …

Advances In Automotive Conversion Coatings During Pretreatment Of The Body Structure: A Review, Mark Doerre, Larry Hibbitts, Gabriela Patrick, Nelson K. Akafuah

Institute of Research for Technology Development Faculty Publications

Automotive conversion coatings consist of layers of materials that are chemically applied to the body structures of vehicles before painting to improve corrosion protection and paint adhesion. These coatings are a consequence of surface-based chemical reactions and are sandwiched between paint layers and the base metal; the chemical reactions involved distinctly classify conversion coatings from other coating technologies. Although the tri-cationic conversion coating bath chemistry that was developed around the end of the 20th century remains persistent, environmental, health, and cost issues favor a new generation of greener methods and materials such as zirconium. Environmental forces driving lightweight material selection …

Magnetic Ordering In A Vanadium-Organic Coordination Polymer Using A Pyrrolo[2,3-D:5,4-D']Bis(Thiazole)-Based Ligand, Yulia A. Getmanenko, Christopher S. Mullins, Vladimir N. Nesterov, Stephanie Lake, Chad Risko, Ezekiel Johnston-Halperin

Chemistry Faculty Publications

Here we present the synthesis and characterization of a hybrid vanadium-organic coordination polymer with robust magnetic order, a Curie temperature T_C of ∼110 K, a coercive field of ∼5 Oe at 5 K, and a maximum mass magnetization of about half that of the benchmark ferrimagnetic vanadium(tetracyanoethylene)_~2 (V·(TCNE)_~2). This material was prepared using a new tetracyano-substituted quinoidal organic small molecule 7 based on a tricyclic heterocycle 4-hexyl-4H-pyrrolo[2,3-d:5,4-d′]bis(thiazole) (C₆-PBTz). Single crystal X-ray diffraction of the 2,6-diiodo derivative of the parent C₆-PBTz, showed a disordered hexyl chain and …

Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman

Chemistry Faculty Publications

Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic …

Highly Thiolated Poly (Beta-Amino Ester) Nanoparticles For Acute Redox Applications, Andrew L. Lakes, David A. Puleo, J. Zach Hilt, Thomas D. Dziubla

Chemical and Materials Engineering Faculty Publications

Disulfides are used extensively in reversible cross-linking because of the ease of reduction into click-reactive thiols. However, the free-radical scavenging properties upon reduction are often under-considered. The free thiols produced upon reduction of this disulfide material mimic the cellular reducing chemistry (glutathione) that serves as a buffer against acute oxidative stress. A nanoparticle formulation producing biologically relevant concentrations of thiols may not only provide ample chemical conjugation sites, but potentially be useful against severe acute oxidative stress exposure, such as in targeted radioprotection. In this work, we describe the synthesis and characterization of highly thiolated poly (β-amino ester) (PBAE) nanoparticles …

Local Deformation And Texture Of Cold-Rolled Aa6061 Aluminum Alloy, Diaoyu Zhou, Wenwen Du, Xiyu Wen, Junwei Qiao, Wei Liang, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Using cold rolling, we plastically deform AA6061 sheets at room temperature and investigate the variations of the microstructures, textures and local deformation of the cold-rolled AA6061 sheets as functions of thickness reduction (Δt/t₀, t₀ and t are the thicknesses of the AA6061 sheet before and after the cold rolling, respectively). The volume fraction of total deformation texture is relatively independent of the thickness reduction for Δt/t₀ ≤ 30%, and becomes an approximately linearly increasing function of the thickness reduction for Δt/t₀ > 30%. Increasing the thickness reduction causes the increase of the Vickers hardness of the …

Ultrafine Mineral Associations In Superhigh-Organic-Sulfur Kentucky Coals, James C. Hower, Debora Berti, Michael F. Hochella Jr.

Center for Applied Energy Research Faculty and Staff Publications

Two high-organic-sulfur Kentucky coals, the eastern Kentucky River Gem coal and the western Kentucky Davis coal, are examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), both including elemental analysis by energy-dispersive spectroscopy (EDS). From the SEM–EDS analysis, it is observed that the western Kentucky coal had areas with Pb and Cd in addition to the expected Fe and S and the eastern Kentucky coal had individual Fe–S-rich areas with La and Ni and with Si, Al, Cr, Ni, and Ti. TEM and selected area electron diffraction (SAED) analyses demonstrate that anglesite with a rim of Pb-bearing amorphous …

Self-Cleaning Nanocomposite Membranes With Phosphorene-Based Pore Fillers For Water Treatment, Joyner Eke, Katherine Elder, Isabel Escobar

Chemical and Materials Engineering Faculty Publications

Phosphorene is a two-dimensional material exfoliated from bulk phosphorus and it possesses a band gap. Specifically, relevant to the field of membrane science, the band gap of phosphorene provides it with potential photocatalytic properties, which could be explored in making reactive membranes that can self-clean. The goal of this study was to develop an innovative and robust membrane that is able to control and reverse fouling with minimal changes in membrane performance. To this end, for the first time, membranes have been embedded with phosphorene. Membrane modification was verified by the presence of phosphorus on membranes, along with changes in …

Gold-Catalyzed Conversion Of Lignin To Low Molecular Weight Aromatics, Yang Song, Justin K. Mobley, Ali Hussain Motagamwala, Mark Isaacs, James E. Dumesic, John Ralph, Adam F. Lee, Karen Wilson, Mark Crocker

Chemistry Faculty Publications

A heterogeneous catalyst system, employing Au nanoparticles (NPs) and Li–Al (1 : 2) layered double hydroxide (LDH) as support, showed excellent activity in aerobic oxidation of the benzylic alcohol group in β-O-4 linked lignin model dimers to the corresponding carbonyl products using molecular oxygen under atmospheric pressure. The synergistic effect between Au NPs and the basic Li–Al LDH support induces further reaction of the oxidized model compounds, facilitating facile cleavage of the β-O-4 linkage. Extension to oxidation of γ-valerolactone (GVL) extracted lignin and kraft lignin using Au/Li–Al LDH under similar conditions produced a range of aromatic monomers in high yield. …

Aging Response And Precipitation Behavior After 5% Pre-Deformation Of An Al-Mg-Si-Cu Alloy, Shuoxun Jin, Tungwai Ngai, Liejun Li, Shian Jia, Tongguang Zhai, Dongjie Ke

Chemical and Materials Engineering Faculty Publications

In this study, Al-1.00 Mg-0.65 Si-0.24 Cu alloy was solution heat-treated, water-quenched, and then pre-deformed for 5% before aging. The peak hardness and yield strength of the pre-deformed sample with subsequent artificial aging were similar to that of a T6 condition sample. It was also found that the pre-deformation treatment could inhibit the negative influence of natural aging to some degree. After seven days of natural aging, the pre-deformed sample obtained better peak hardness and yield strength upon artificial aging than the sample without pre-deformation. In addition, the pre-deformation treatment could reduce 50% of the artificial aging time to reach …

Schlieren Visualization Of Shaping Air During Operation Of An Electrostatic Rotary Bell Sprayer: Impact Of Shaping Air On Droplet Atomization And Transport, Adnan Darwish Ahmad, Ahmad M. Abubaker, Ahmad A. Salaimeh, Nelson K. Akafuah

Institute of Research for Technology Development Faculty Publications

Electrostatic rotary bell sprayers (ERBSs) are widely used in the automotive industry. In ERBS, atomization is facilitated using centrifugal forces which disintegrate the paint film inside the cup into droplets at the cup edge. The droplets are then transported by the flow of a shaping air (SA) and electrostatic forces to a target surface; the characteristics of these droplets dramatically influence the quality of a painted surface and the painting transfer efficiency. In the current paper, a novel Schlieren-based visualization of the shaping air in the absence of paint droplets was performed during a qualitative investigation to delineate shaping air …

Investigation Of The Use Of A Bio-Derived Solvent For Non-Solvent-Induced Phase Separation (Nips) Fabrication Of Polysulfone Membranes, Xiaobo Dong, Amna Al-Jumaily, Isabel Escobar

Chemical and Materials Engineering Faculty Publications

Organic solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc), have been traditionally used to fabricate polymeric membranes. These solvents may have a negative impact on the environment and human health; therefore, using renewable solvents derived from biomass is of great interest to make membrane fabrication sustainable. Methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (Rhodiasolv PolarClean) is a bio-derived, biodegradable, nonflammable and nonvolatile solvent. Polysulfone is a commonly used polymer to fabricate membranes due to its thermal stability, strong mechanical strength and good chemical resistance. From cloud point curves, PolarClean showed potential to be a solvent for polysulfone. Membranes prepared with PolarClean were investigated in terms of …

Research And Development Of Powder Brazing Filler Metals For Diamond Tools: A Review, Fei Long, Peng He, Dusan P. Sekulic

Mechanical Engineering Faculty Publications

Powder brazing filler metals (PBFMs) feature a number of comparative advantages. Among others, these include a low energy consumption, an accurate dosage, a good brazeability, a short production time, and a high production efficiency. These filler metals have been used in the aerospace, automobile, and electric appliances industries. The PBFMs are especially suitable for diamond tools bonding, which involves complex workpiece shapes and requires accurate dosage. The recent research of PBFMs for diamond tools is reviewed in this paper. The current applications are discussed. The CuSnTi and Ni-Cr-based PBFMs have been the two commonly used monolayer PBFMs. Thus, the bonding …