Engineering Commons^™

Understanding The Factors That Control Theformation And Morphology Of Zn5(Oh)8(No3)2⋅2h2othrough Hydrothermal Route, Xu Liu, Chunrui Wang, Xiaoyun Liu, Lizhi Ouyang, Ziyin You, Yeqing Lu, Xiaoshuang Chen

Mathematical Sciences Faculty Research

The influence of the choice of ethanol-water volume ratio, concentration of zinc salt, and ZnO buffer layer on the formation andmorphology of Zn5(OH)8(NO3)2⋅2H2O grown from the hydrothermal route was systematically discussed. Experimental resultssuggested that Zn5(OH)8(NO3)2⋅2H2O rectangle sheets and Zn5(OH)8(NO3)2⋅2H2O upright-standing plates were obtained bylimiting ethanol-water volume ratio. The concentration of zinc salt was crucial for getting phase-pure Zn5(OH)8(NO3)2⋅2H2O. Thepresence of ZnO buffer layer could lead to the that chemical composition of product grown on the substrate was totally differentfrom the product grown in the solution. Possible formation mechanism of Zn5(OH)8(NO3)2⋅2H2O was also studied. Ramanspectrum of Zn5(OH)8(NO3)2⋅2H2O displays a complex behavior …

Dielectric Properties Of Polymer–Particle Nanocomposites Influenced By Electronic Nature Of Filler Surfaces, Sasidhar Siddabattuni, Thomas P. Schuman, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

The interface between the polymer and the particle has a critical role in altering the properties of a composite dielectric. Polymer-ceramic nanocomposites are promising dielectric materials for many electronic and power devices, combining the high dielectric constant of ceramic particles with the high dielectric breakdown strength of a polymer. Self-assembled monolayers of electron rich or electron poor organophosphate coupling groups were applied to affect the filler–polymer interface and investigate the role of this interface on composite behavior. The interface has potential to influence dielectric properties, in particular the leakage and breakdown resistance. The composite films synthesized from the modified filler …

An Examination Of The Potential Of Building Information Modelling To Increase The Efficiency Of Irish Contractors On Design And Build Projects, Charles Anthony Mitchell, Myles Keaveney

Conference papers

Competition between Irish contractors is more aggressive than ever before. In the current economic climate an ability to construct with greater efficiency could ensure a company’s survival. The purpose of this research was to determine the extent to which efficiency benefits could be realised by contractors on design and build projects as a result of implementing a revolutionary process referred to as Building Information Modelling (BIM). After a critical analysis on all aspects of BIM in the literature review, questionnaires were sent to establish the success of this system in the US and also in the comparatively few Irish firms …

Metamaterial Structure Design Optimization: A Study Of The Cylindrical Cloak, Jason V. Paul

Theses and Dissertations

Previously, Transformational Optics (TO) has been used as a foundation for designing cylindrical cloaks. The TO method uses a coordinate transform to dictate an anisotropic material parameter gradient in a cylinder coating that guides waves around the cylinder to reduce the Radar Cross Section (RCS). The problem is that the material parameters required for the TO cloak are not physically realizable and thus must be approximated. This problem is compounded by the fact that any approximation deviates from the ideal design and will allow fields to penetrate the cloak layer and interact with the object to be cloaked. Since the …

Quantum Man, Julian Voss-Andreae

The Transdisciplinary STEAM+ Journal

According to quantum physics, the world is fundamentally quite different than it seems. Drawing inspiration from the underlying nature of reality, former quantum physicist Julian Voss-Andreae created an image of a walking human as a quantum object. Made up of parallel sheets of steel, the sculpture is a metaphor for the counter-intuitive world of quantum physics. Symbolizing the dual nature of matter with the appearance of classical reality on the surface and cloudy quantum behavior underneath, the sculpture seems to consist of solid steel when seen from the front, but dissolves into almost nothing when seen from the side.

Migration Grid #26, Stanton Hunter

The Transdisciplinary STEAM+ Journal

This work is inspired by invisible sky grids formed by Ultra Violet (UV) light researchers discovered that guide Monarch butterflies on their migration from the mid-western United States to the Sierra Madre Mountains in Mexico. I use terrestrial material, clay, to make something celestial. Earth, associated with mass and permanence, is translated into these shifting, ephemeral, and ethereal sky-forms. The work encompasses void more than object and the complex shadows they cast are immaterial. Together, the objects and shadows point to what can’t be seen, at least by the human eye.

First Principles Study On Inp (001)-(2 × 4) Surface Oxidation, Santosh Kc, Weichao Wang, Hong Dong, Ka Xiong, Roberto Longo, Robert Wallace, Kyeongjae Cho

Faculty Publications

A theoretical study of the oxidation of InP(001)-(2 × 4) surface is performed using density functional theory methods. Our results on surface oxidation show that the oxygen adsorption does not produce any gap states in the bulk InP band gap, due to the saturation of surface In dangling bonds, whereas substitutional oxygen atoms produce gap states. This study also shows that the surface stability increases with the oxygen content, indicating a strong tendency for surface oxidation. Our results help to clarify the origin of surface gap states upon surface oxidation and provide an insight at the atomic level the mechanism …

Stress Corrosion Cracking Susceptibility Of Ultrafine Grained Al-Mg-Sc Alloy, G. R. Argade, N. Kumar, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

General corrosion and stress corrosion cracking (SCC) behavior of coarse grained, fine grained and ultrafine grained (UFG) AA5083 and Al-Mg-Sc-Zr alloy in different thermomechanical conditions were studied in the present work. Friction stir processing (FSP) was carried out to refine the grain size. The average grain size achieved after FSP for AA5083 was 7±3μm, whereas that for Al-4Mg-0.8Sc-0.08Zr was 0.39±0.16μm with 100% UFG microstructure. Linear polarization resistance and cyclic polarization techniques were used to study general corrosion behavior of these alloys in 3.5wt% NaCl solution. The UFG microstructure showed the highest polarization resistance (Rp) of ~93kΩ which increased to ~160kΩ …

Study Of The Growth And Switching Kinetics On Ferroelectric Nanocrystals Of Copolymer Vinylidene Fluoride And Trifluoroethylene On An Atomic Force Microscope, R. V. Gaynutdinov, O. A. Lysova, A. L. Tolstikhina, V. M. Fridkin, S. G. Yudin, Stephen Ducharme

Stephen Ducharme Publications

The growth of nanocrystals obtained from Langmuir-Blodgett films of ferroelectric copolymer consisting of 70% vinylidene fluoride and 30% trifluoroethylene has been investigated by atomic force microscopy (AFM). The radius and concentration of nanocrystals are found to depend on the annealing time of the film. A model for nanocrystal growth is proposed which yields adequate time dependences for nanocrystal size parameters. The switching kinetics of individual ferroelectric nanocrystals with an average diameter of 100–200 nm and a height of 15–20 nm has been investigated in the piezoelectric response mode. It is shown that the switching of nanocrystals has an activation character.

High-Stress Shear-Induced Crystallization In Isotactic Polypropylene And Propylene/Ethylene Random Copolymers, Zhe Ma, Lucia Fernandez-Ballester, Dario Cavallo, Tim Gough, Gerrit W. M. Peters

Department of Mechanical and Materials Engineering: Faculty Publications

Crystallization of an isotactic polypropylene (iPP) homopolymer and two propylene/ethylene random copolymers (RACO), induced by high-stress shear, was studied using in situ synchrotron wide-angle X-ray diffraction (WAXD) at 137 °C. The “depth sectioning” method (Fernandez-Ballester, Journal of Rheology 53:5 (2009), pp. 1229−1254) was applied in order to isolate the contributions of different layers in the stress gradient direction and to relate specific structural evolution to the corresponding local stress. This approach gives quantitative results in terms of the specific length of fibrillar nuclei as a function of the applied stress. As expected, crystallization becomes faster with increasing stress—from the inner …

Study Of An Alternative Process For Oxidizing Vapor Grown Carbon Nanofibers Using Electron Beam Accelerators, Maria Cecília Evora, Donald A. Klosterman, Khalid Lafdi, Lingchuan Li, L.G.A. Silva

Chemical and Materials Engineering Faculty Publications

The use of a high-energy electron beam was explored in this study as an alternative technique for oxidizing vapor grown carbon nanofiber surfaces. The radiation exposures were carried out at three different electron beam facilities with beam energies of 1.5, 3.0 and 4.5 MeV and radiation doses ranging from 1000 to 3500 kGy. XPS analysis showed that oxygen was readily incorporated on the surface: the ratio O1s/C1s increased approximately by a factor of 4 when the carbon nanofibers were irradiated at 3500 kGy. The oxidized nanofibers exhibited better dispersion in a water/methanol solution (50% v/v) than as-received nanofibers. Raman spectroscopy …

Dc, Rf, And Thermal Characterization Of High Electric Field Induced Degradation Mechanisms In Gan-On-Si High Electron Mobility Transistors, Matthew Anthony Bloom

Master's Theses

Gallium Nitride (GaN) high electron mobility transistors (HEMTs) are becoming increasingly popular in power amplifier systems as an alternative to bulkier vacuum tube technologies. GaN offers advantages over other III-V semiconductor heterostructures such as a large bandgap energy, a low dielectric constant, and a high critical breakdown field. The aforementioned qualities make GaN a prime candidate for high-power and radiation-hardened applications using a smaller form-factor. Several different types of semiconductor substrates have been considered for their thermal properties and cost-effectiveness, and Silicon (Si) has been of increasing interest due to a balance between both factors.

In this thesis, the DC, …

Bacterial Growth On Metal And Non-Metal Surfaces In A Static Bioreactor, Rolan Yuk Loong Liong

Master's Theses

Research was conducted to observe bacterial growth on the surface of metals in a static bioreactor. Metal and non-metal samples were subjected to bacterial exposure (1 day and 9 days). The metal samples were surface treated prior to bacterial exposure. The microstructures of the surface treated samples were analyzed by optical microscopy. After exposure, the microstructures of the samples were analyzed by scanning electron microscopy (SEM). The analysis suggested that microbial attachment on the surface was related to the underlying microstructure of steel. The preferential attachment of microbes could potentially be influenced by cathodic and anodic regions created by the …

An In Situ Experimental Study Of Grain Growth In A Nanocrystalline Fe91ni8zr1 Alloy, Hasan Kotan, Kris A. Darling, Mostafa Saber, Ronald O. Scattergood, Carl C. Koch

Mechanical and Materials Engineering Faculty Publications and Presentations

Grain growth and microstructural evolution of thermally stabilized Fe91Ni8Zr1 were investigated by in situ and ex situ studies. Our investigations suggest that the microstructural evolution is fairly slow and the microstructure shows stabilization up to about 700 °C. Above this temperature, a certain fraction of grains grow abnormally into the nanocrystalline matrix, resulting in a bimodal microstructure and causing the complete loss of thermal stability. The reason for abnormal grain growth and the loss of thermal stability is identified as the appearance of the fcc γ-phase and consequent reduction in the total area of grain boundaries and the overall stored …

High Performance Membrane Electrode Assembly With Low Platinum Loadings Prepared By Atomic Layer Deposition For Pemfc Application, Ting Shu, Shi-Jun Liao, Chien-Te Hsieh, Ay Su

Journal of Electrochemistry

A high performance membrane electrode assembly (MEA) with low platinum loadings was successfully prepared with atomic layer deposition (ALD) technique. The anode of the MEA was prepared by depositing platinum on the carbon paper substrate, which was prepared by coating the slurry of carbon black (XC-72R) and Teflon, followed by drying and calcining at 350 °C. The MEAs consisted of the ALD anode or commercial catalyst anode, pretreated Nafion membrane (Nafion-117) and commercial cathode. Performances of MEAs were measured by single cell testing, and the anodes and MEAs were characterized by CV, SEM, TEM and XRD. The results revealed that …

Electrochemical Performance Of Fe3O4/C Composites As Negative Material For Lithium-Ion Batteries, Jun-Jie Cai, Shu Yao, Ze-Sheng Li, Hui Meng, Pei-Kang Shen

Journal of Electrochemistry

The Fe₃O₄/Carbon composites have been synthesized through coprecipitation pathway and by insitu aniline polymerization as a carbon source. Structural characterization and morphological study of the composites were investigated by using XRD, SEM and TEM techniques. The results showed that the nanosized Fe₃O₄ particles (40 ~ 80 nm) were encapsulated in the amorphous carbon. During the electrochemical tests, the Fe₃O₄/C composites exhibited high capaticity and excellent cycle ability, the retention of capaticity was about 1000 mAh·g^-1 after 30 cycles of charge/discharge tests at 50 mA·g^-1.

A Comparative Study Of Charge-Discharge Behaviors Of α-Pbo2 And β-Pbo2 Cathodes, Cong-Ying Cui, Xue-Mei Ma, De-Long Kong, Hou-Yi Ma

Journal of Electrochemistry

The α-PbO₂ and β-PbO₂ powders were prepared using simple chemical synthetic methods, and their crystalline structures and surface morphologies were characterized with X-ray powder diffraction spectroscopy and scanning electron microscopy. Using the as-synthesized α-PbO₂ and β-PbO₂ powders as positive active materials, the electrochemical performance of the two PbO₂ materials was investigated by means of cyclic voltammetry, galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy. The results indicate that the discharge capacity of α-PbO₂ electrode is larger than that of β-PbO₂; moreover, the composite electrodes made by α-PbO₂ and β-PbO₂ mixtures with …

An In Situ Ftir Spectroelectrochemical Study On Methanol Oxidation At Pt-Mo2C/Gc Catalyst, Hai-Ping Huang, Xi-Yu Yao, Pei-Kang Shen

Journal of Electrochemistry

A 40% Pt on Mo₂C/GC catalyst has been prepared by ion exchange method. The mechanism of methanol electrooxidation on Pt-Mo₂C/GC and commercial Pt/C catalysts in acidic media was studied by cyclic voltammetry, XRD measurements and in-situ Fourier transform infrared spectroelectrochemistry. The results revealed that the Pt nanoparticles were uniformly dispersed on Mo₂C/GC with an average particle size of 3 nm. The cyclic voltammetric and chronopotentiometric experiments indicated that Pt-Mo₂C/GC catalyst exhibited a better performance for methanol oxidation than that of Pt/C in acid solution. A negative shift over 90 mV of the …

Applications Of Ellipsometry In The Investigations Of Electrode-Solution Interface, Jing-Lei Lei, Liang-Liu Wu, Ling-Jie Li, Sheng-Mao Wu, Sheng-Tao Zhang

Journal of Electrochemistry

Ellipsometry is an optical technique with high-sensitivity to quantitatively obtain surface/interface properties such as thickness andrefractive index by analyzing the changes in polarized light reflected from the surface/interface. Its noncontacting and nondestructivenature makes it possible to acquire thein situreal-time information of the change at the surface/interface. Therefore, ellipsometry has been used widely in the electrochemical investigations. In this paper, based on the brief introduction of the measurementprinciple of ellipsometry, the current progress and the future trends of ellipsometry in electrochemistry arediscussed. The applications of ellipsometry in the fields of conversion and storage of electrochemical energy, electrochemistry ofmaterials science,electroanalysisand bioelectrochemistry are …

Oxygen Reduction Reaction On Glycin Modified Pt(111) Electrode, Ming-Fang Li, Jing Kang, Ling-Wen Liao, Yan-Xia Chen, Shen Ye

Journal of Electrochemistry

O

xygen reduction reaction (ORR) on glycin (NH₂CH₂COOH) modified Pt(111) electrode has been investigated using hanging meniscus rotating disk electrode system (HMRD) in 0.05 mol•L^-1 H₂SO₄ and 0.1 mol•L^-1 HClO₄ solutions, respectively. Cyclic voltammograms of the glycin modified Pt (111) electrode measured in 0.05 mol•L^-1 H₂SO₄ solution similar to that of CN^- modified Pt(111) electrodes, demonstrating that sulfate adsorption is strongly inhibited at the glycin modified Pt(111). From the polarization curve of ORR recorded in 0.05 mol•L^-1 H₂SO₄ solution, it is …

Porous Electrodes With High Pt Utilization Obtained By Ion-Exchange/Electrodeposition, Si-Guo Chen, Wei Ding, Xue-Qiang Qi, Li Li, Zi-Hua Deng, Zi-Dong Wei

Journal of Electrochemistry

We report a novel method based on ion-exchange/electrodeposition (IEE) for constructing high Pt utilization porous electrodes. The electrode prepared using IEE was assessed by linear sweep voltammetry (LSV), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and single cell test. The preliminary results show that the undesired ion-exchange between Pt anion and surface functional group in carbon black can be eliminated through the electrode preparation process, and every Pt particle prepared by IEE is expected to be deposited on the three-phase reaction zone and thus can be fully utilized in fuel cell reactions. The Pt particle size, shape and distribution …

Effect Of Ti/Pbo2 Electrodes Doped With Different Elements On Electrocatalytic Oxidation Characteristics Of Phenol, Xiao-Lei Liu, Yuan-Yuan Dan, Hai-Yan Lu, Hai-Bo Lin, Ming-Li Ouyang, Chuan-Jun Yun

Journal of Electrochemistry

Three types of electrodes, namely, Ti/PbO₂, F-doped PbO₂ (Ti/PbO₂-F) and nano-Co₃O₄-doped PbO₂ (Ti/PbO₂+Nano-Co₃O₄) electrodes, were prepared by electro-deposition method on the Ti substrate with the interlayer of SnO₂-Sb₂O₅. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the compositions, structures and film morphologies of the electrodes. Electrocatalytic oxidation characteristics to phenol on the prepared electrodes were investigated by electrochemical method. The experimental results showed that compared with the Ti/PbO₂ electrode, the potentials of oxygen …

A Dft Calculation Screening Of Pt-Based Bimetallic Catalysts For Oxygen Reduction, Li-Hui Ou, Sheng-Li Chen

Journal of Electrochemistry

Developing Pt-lean catalysts for oxygen reduction reaction (ORR) is the key for large-scale application of proton exchange membrane fuel cell (PEMFC). In this paper, we have proposed a multiple-descriptor strategy for screening efficient and durable ORR alloy catalysts of low Pt content. We argue that an ideal Pt-based bimetallic alloy catalyst for ORR should possess simultaneously negative alloy formation energy, negative surface segregation energy of Pt and a lower oxygen binding ability than pure Pt. By performing detailed DFT calculations on the thermodynamics, surface chemistry and electronic properties of various Pt-M alloys (M refers to non-precious transition metals in the …

Sodium Carbonate Catalyzed Photoelectrochemical Water Splitting Over Tio2 Nanotubes Photoanode, De-Sheng Kong, Jing Wang, Xue-Di Zhang, Xi Zhao, Chao Wang, Yuan-Yuan Feng, Wen-Juan Li

Journal of Electrochemistry

Surface recombination of the photogenerated electron-hole pairs at semiconductor/electrolyte interface is one of the most essential reasons responsible for lowering photoconversion efficiency (Φ) of light to chemical energy for photoelectrochemical (PEC) water splitting reaction. In this paper, the catalytic effect of sodium carbonate on the oxygen evolution reaction (OER) over TiO₂ nanotubes photoanode during PEC water splitting was investigated by performing photocurrent and ac impedance measurements. It was demonstrated that the addiction of 1 mmol•L^-1 Na₂CO₃ in 0.5 mol•L^-1 NaClO₄ electrolyte can effectively improve the charge transfer properties for the photogenerated holes across …

Material Characterization And The Effects Of Moisture And Drying On Injection Molded Torlon 5030, Michael R. Di Re

Master's Theses

The effects of water absorption and drying were studied on injection molded Torlon 5030, a high performance thermoplastic fabricated by Solvay Specialty Polymers. Torlon 5030 contains 30% by weight glass fibers in a polyamide-imide base resin. The objective behind this work was to test and better define relevant properties for industrial applications using this material. While the material design guide offers information on many mechanical properties including tensile, fatigue, and creep data; there is little to no publicly published data on the effects of water absorption and any subsequent drying of Torlon 5030. Blistering was also studied. With exposure to …

Compositional Tuning Of Structural Stability Of Lithiated Cubic Titania Via A Vacancy-Filling Mechanism Under High Pressure, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

Experimental and theoretical studies on the compositional dependence of stability and compressibility in lithiated cubic titania are presented. The crystalline-to-amorphous phase transition pressure increases monotonically with Li concentration (from ∼17.5  GPa for delithiated to no phase transition for fully lithiated cubic titania up to 60 GPa). The associated enhancement in structural stability is postulated to arise from a vacancy filling mechanism in which an applied pressure drives interstitial Li ions to vacancy sites in the oxide interior. The results are of significance for understanding mechanisms of structural response of metal oxide electrode materials at high pressures as well as emerging …

High Strain Rate Superplasticity In Friction Stir Processed Ultrafine Grained Mg-Al-Zn Alloys, A. Mohan, W. Yuan, R. S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Friction stirs processing of a rolled AZ31 alloy, and a high pressure die cast AZ91 alloy produced ultrafine grained materials with average grain size of 0.8μm and 0.5μm, respectively. Tensile testing was done in the temperature range of 210-360°C and strain rate range of 1x10^-4-3x10^-2s^-1. Higher amounts of Β-precipitates in AZ91 thermally stabilized the microstructure up to 330°C. Friction processed ultrafine grain AZ91 exhibited high strain rate super plasticity at all tested temperatures. The best elongation of 1251% was achieved at a strain rate of 1x10^-2s^-1 and temperature of 330°C. The …

Guided Wave-Based J-Integral Estimation For Dynamic Stress Intensity Factors Using 3d Scanning Laser Doppler Vibrometry, J. Ayers, Christopher Todd Owen, Eric D. Swenson, Anindya Ghoshal, V. Weiss

Faculty Publications

The application of guided waves to interrogate remote areas of structural components has been researched extensively in characterizing damage. However, there exists a sparsity of work in using piezoelectric transducer-generated guided waves as a method of assessing stress intensity factors (SIF). This quantitative information enables accurate estimation of the remaining life of metallic structures exhibiting cracks, such as military and commercial transport vehicles. The proposed full wavefield approach, based on 3D laser vibrometry and piezoelectric transducer-generated guided waves, provides a practical means for estimation of dynamic stress intensity factors (DSIF) through local strain energy mapping via the J-integral. Strain energies …

Effect Of Friction Stir Processing On The Tensile And Fatigue Behavior Of A Cast A206 Alloy, R. Kapoor, K. Kandasamy, R. S. Mishra, J. A. Baumann, G. Grant

Materials Science and Engineering Faculty Research & Creative Works

The microstructure of cast Al alloy A206 was modified using friction stir processing (FSP) to eliminate porosity, break down intermetallic particles and refine the grains. The inference from differential scanning calorimetry is that the nugget region of the as-FSP material contained primarily GP zones. Uniaxial tensile tests and bending fatigue tests were carried out at room temperature on A206 alloy in the cast and T4 conditions and after FSP with different heat treatments - as-FSP, FSP and aging, and FSP with solutionizing and aging. These produced varied microstructures with combinations of pores, grain sizes, precipitate types and particle sizes. The …

Interfacial Bonding And Electronic Structure Of Hfo2/Gasb Interfaces: A First-Principles Study, Ka Xiong, Wei-Hua Wang, Dmitry Zhernokletov, Santosh Kc, Roberto Longo, R. Wallace, Kyeongjae Cho

Faculty Publications

The interfacial bonding and electronic structure of HfO2/GaSb interfaces has been investigated through first principles calculations. The calculated electronic structures of these interfaces reveal that some O-rich interfaces are semiconducting interfaces without any gap states. In contrast, for the interfaces with lower interfacial O content, gap states appear in the GaSb band gap, close to the conduction band. The valence band offsets are found to vary from 2.2 eV to 3.6 eV, depending on the interfacial O content. Our results suggest that GaSb is a suitable material to form high quality interface with HfO2.