Passivation Behavior Of Aluminum Alloy During Electrochemical Machining And Its Effects On The Machining Performance,
2014
School of Material Science & Engineering, Nanchang Hangkong University, National Defense Key Laboratory of Light Alloys Processing Science and Technology, Nanchang 330063, China;
Passivation Behavior Of Aluminum Alloy During Electrochemical Machining And Its Effects On The Machining Performance, Li-Min Jiang, Wen-Bo Deng, Jun-Long Ying
Journal of Electrochemistry
The passivation behavior of aluminum alloy during electrochemical machining was investigated and discussed. The effects of processing voltage, current density, space of electrodes and electrolyte composition on electrochemical machining performance were explored. The results indicate that the electrochemical machining aluminum alloy in the composite electrolyte system containing NaNO3 and NaF existed passivation phenomenon. Passivation action decreaseed the current efficiency and made it varied greatly with the current density. Also the passivation shifted the interspace characteristic curve of electrode notably to a negative direction. There was not passivation phenomenon in the composite electrolyte system containing the same concentrations of NaCl …
Fabrication And Impedance Performance Of Gradient Lani0.6Fe0.4O3-δ-Gd0.2Ce0.8O2 Composite Cathodes For Intermediate Temperature Solid Oxide Fuel Cell,
2014
Institute of Fuel Cell, School of Mechanical Engineering, Shanghai Jiaotong University, Shanghai 200240, China;
Fabrication And Impedance Performance Of Gradient Lani0.6Fe0.4O3-δ-Gd0.2Ce0.8O2 Composite Cathodes For Intermediate Temperature Solid Oxide Fuel Cell, Yang Li, Bo Huang, Meng Yuan, Zhi-Qiu Zhang, Zong-Yao Liu, Xu-Chen Tang, Xin-Jian Zhu
Journal of Electrochemistry
A LNF-GDC composite cathode with a gradual change in the composition between ScSZ electrolyte and LNF cathode was fabricated to reduce the cathode polarization resistance (Rp). The gradual change in composition between ScSZ electrolyte and LNF cathode shows the decreases in the charge transfer resistance (Rct) and gas phase diffusion resistance (Rd). The results revealed that the Rp value, measuring 0.452 Ω·cm2 at 750 °C, was the lowest for LNF-GDC composite cathodes with three layers and gradient changes in composition between ScSZ and LNF (Cathode C),, whereas the Rp value of 70%LNF-30%GDC composite …
Electrochemical Performance Of Si-C Composites Prepared By Discharge-Plasma Assisted Milling,
2014
School of Materials Science and Engineering, South China University of Technology, Guangdong Key Lab of Advanced Materials for Energy Storage, Guangzhou 510640, China;
Electrochemical Performance Of Si-C Composites Prepared By Discharge-Plasma Assisted Milling, Yu-Long Chen, Ren-Zong Hu, Hui Liu, Wei Sun, Min Zhu
Journal of Electrochemistry
Silicon-carbon (Si-C) composites, with microstructure of multi-scaled Si particles being homogenously dispersed in micro-sized carbon matrix, had been prepared by dielectric barrier discharge plasma assisted two-step milling for the first time. The Si-C composite anode had a discharge capacity of 1259 mAh·g-1 at the first cycle, while the capacity retained 474 and 396 mAh·g-1 after 20 and 100 cycles, respectively. Charge-discharge curves and AC impedance response indicated that both silicon and carbon phases in the composite anode were involved during the lithiation/delithiation reactions and the electron transport resistance in the Si-C composite anode was much lower than that …
Design And Development Of A Novel Glucose Biosensor Based On The Ferrocene-Functionalized Fe3O4 Nanoparticles/Carbon Nanotubes/Chitosan Nanocomposite Film Modified Electrode,
2014
Department of Pharmaceutical Analysis of the Fujian Medical University, Fuzhou 350004, China
Design And Development Of A Novel Glucose Biosensor Based On The Ferrocene-Functionalized Fe3O4 Nanoparticles/Carbon Nanotubes/Chitosan Nanocomposite Film Modified Electrode, Hua-Ping Peng, Dai-Jun Zha, Wei Chen, Ai-Lin Liu, Xin-Hua Lin
Journal of Electrochemistry
A novel platform for the fabrication of glucose biosensor was successfully constructed by entrapping glucose oxidase (GOD) in a ferrocene monocarboxylic acid-aminated Fe3O4 magnetic nanoparticles conjugate (FMC-AFNPs)/chitosan (CS)/multiwall carbon nanotubes (MWNTs) nanocomposite. The formation of FMC-AFNPs could effectively prevent the leakage of ferrocene and retain its electrochemical activity. This GOD/FMC-AFNPs/CS/MWNTs matrix provided a biocompatible microenvironment for retaining the native activity of the immobilized GOD. Moreover, the presence of MWNTs enhanced the charge-transport properties of the composite and facilitated electron transfer between the GOD and the electrode for the electrocatalysis of glucose. Under the optimal conditions the designed …
A Systematic Study Of The Optical And Electrical Properties Of Ge1-YSnY And Ge1-X-YSiXSnY Semiconductor Alloys,
2014
Air Force Institute of Technology
A Systematic Study Of The Optical And Electrical Properties Of Ge1-YSnY And Ge1-X-YSiXSnY Semiconductor Alloys, Thomas R. Harris
Theses and Dissertations
In order to fully utilize newly developed Ge1-ySny and Ge1-x-ySixSny materials for new novel optoelectronic devices, the optical and electrical properties of these alloys were investigated using photoluminescence (PL) and Hall-effect measurements. Direct bandgap PL emission was observed from almost all the samples, making them very promising candidates for Si-based light emitting devices. T-dependent PL studies also indicate that the indirect-to-direct bandgap transition of Ge1-ySny alloys might take place at a much lower Sn content than the theory predicts. T-dependent Hall-effect measurements showed both degenerate parallel conducting layers as …
Tunneling Into The Mott Insulator Sr2Iro4,
2014
University of Kentucky
Tunneling Into The Mott Insulator Sr2Iro4, John A. Nichols, Noah Bray-Ali, Armin Ansary, Gang Cao, Kwok-Wai Ng
Center for Advanced Materials Faculty Publications
We studied the single-layered iridate Sr2IrO4 with a scanning tunneling microscope. The finite low temperature conductance enables the electronic structure of this antiferromagnetic Mott insulator to be measured by tunneling spectroscopy. We imaged the topography of freshly cleaved surfaces and measured differential tunneling conductance at cryogenic temperatures. We found the Mott gap in the tunneling density of states to be 2Δ=615 meV. Within the Mott gap, additional shoulders are observed which are interpreted as inelastic loss features due to magnons.
Mechanical Properties Of Components Fabricated With Open-Source 3-D Printers Under Realistic Environmental Conditions,
2014
Michigan Technological University
Mechanical Properties Of Components Fabricated With Open-Source 3-D Printers Under Realistic Environmental Conditions, B. M. Tymrak, M Kreiger, Joshua M. Pearce
Department of Materials Science and Engineering Publications
he recent development of the RepRap, an open-source self-replicating rapid prototyper, has made 3-D polymer-based printers readily available to the public at low costs ( < $500). The resultant uptake of 3-D printing technology enables for the first time mass-scale distributed digital manufacturing. RepRap variants currently fabricate objects primarily from acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA), which have melting temperatures low enough to use in melt extrusion outside of a dedicated facility, while high enough for prints to retain their shape at average use temperatures. In order for RepRap printed parts to be useful for engineering applications the mechanical properties of printed parts must be known. This study quantifies the basic tensile strength and elastic modulus of printed components using realistic environmental conditions for standard users of a selection of open-source 3-D printers. The results find average tensile strengths of 28.5 MPa for ABS and 56.6 MPa for PLA with average elastic moduli of 1807 MPa for ABS and 3368 MPa for PLA. It is clear from these results that parts printed from tuned, low-cost, open-source RepRap 3-D printers can be considered as mechanically functional in tensile applications as those from commercial vendors.
The Structure And Properties Of Zinc Aluminophosphate Glasses,
2014
Missouri University of Science and Technology
The Structure And Properties Of Zinc Aluminophosphate Glasses, Charmayne E. Smith (Lonergan), Richard K. Brow, Lionel Montagne, Bertrand Revel
Materials Science and Engineering Faculty Research & Creative Works
The glass forming region of the ZnO-Al2O3-P2O5 (ZAP) system was determined and the structures and properties of the glasses were characterized. For glasses with a constant O/P ratio, i.e., with similar average phosphate anion distributions, and with increasing alumina content, there is an increase in molar volume and glass transition temperature and a decrease in density and refractive index. The structures of the ZAP glasses were characterized by Raman spectroscopy, 31P and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, and high pressure liquid chromatography (HPLC). Systematically shorter phosphate …
Compounds And Methods For Reducing Oxidative Stress,
2014
University of Kentucky
Compounds And Methods For Reducing Oxidative Stress, Thomas Dziubla, J. Zach Hilt, Dipti Biswal, David B. Cochran, Paritosh Wattamwar
Chemical and Materials Engineering Faculty Patents
Antioxidant polymeric compounds are provided that comprise a plurality of monomeric portions, where each monomeric portion includes an antioxidant molecule interposed between at least two acrylate molecules, and where at least one acrylate molecule of each monomeric portion is linked by a diamine molecule to an acrylate molecule of an adjacent monomeric portion to thereby form the polymer. Methods of synthesizing polymeric compounds and methods of using the antioxidant polymeric compounds to reduce oxidative stress are also provided.
Nanostructured Dielectric Materials For High Energy Density Multilayer Ceramic Capacitors,
2014
Missouri University of Science and Technology
Nanostructured Dielectric Materials For High Energy Density Multilayer Ceramic Capacitors, Fatih Dogan, Alan Devoe, Ian Burn
Materials Science and Engineering Faculty Research & Creative Works
A multilayer ceramic capacitor, having a plurality of electrode layers and a plurality of substantially titanium dioxide dielectric layers, wherein each respective titanium dioxide dielectric layer is substantially free of porosity, wherein each respective substantially titanium dioxide dielectric layer is positioned between two respective electrode layers, wherein each respective substantially titanium dioxide dielectric layer has an average grain size of between about 200 and about 400 nanometers, wherein each respective substantially titanium dioxide dielectric layer has maximum particle size of less than about 500 nanometers. Typically, each respective substantially titanium dioxide dielectric layer further includes at least one dopant selected …
Nanostructured Dielectric Materials For High Energy Density Multilayer Ceramic Capacitors,
2014
Missouri University of Science and Technology
Nanostructured Dielectric Materials For High Energy Density Multilayer Ceramic Capacitors, Fatih Dogan, Alan Devoe, Ian Burns
Materials Science and Engineering Faculty Research & Creative Works
A multilayer ceramic capacitor, having a plurality of electrode layers and a plurality of substantially titanium dioxide dielectric layers, wherein each respective titanium dioxide dielectric layer is substantially free of porosity, wherein each respective substantially titanium dioxide dielectric layer is positioned between two respective electrode layers, wherein each respective substantially titanium dioxide dielectric layer has an average grain size of between about 200 and about 400 nanometers, wherein each respective substantially titanium dioxide dielectric layer has maximum particle size of less than about 500 nanometers. Typically, each respective substantially titanium dioxide dielectric layer further includes at least one dopant selected …
Electronic Structure Characterization Of Hybrid Materials,
2014
University of South Florida
Electronic Structure Characterization Of Hybrid Materials, Zhi Li
USF Tampa Graduate Theses and Dissertations
In this dissertation, the studies aim to characterize the electronic structure at the internal interface of hybrid materials. The characterization challenge is originating from the spectral superposition of hybrid constituents. A characterization protocol based on photoemission spectroscopy (PES) was developed and applied to investigate the orbital alignment at the internal interface of the oligothiophene-TiO2 and ArS-CdSe hybrid materials by characterizing the individual constituents and the assembly hybrids respectively. Electrospray deposition technique was used to deposit targeting materials which enabled preparation of thin films in vacuum minimizing ambient contaminations while transmission electron microscopy (TEM) was used to investigate the morphology and …
Large-Scale Solution Synthesis Of Narrow Graphene Nanoribbons,
2014
University of Nebraska–Lincoln
Large-Scale Solution Synthesis Of Narrow Graphene Nanoribbons, Timothy H. Vo, Mikhail Shekhirev, Donna A. Kunkel, Martha D. Morton, Eric Berglund, Lingmei Kong, Peter M. Wilson, Peter A. Dowben, Axel Enders, Alexander Sinitskii
Nebraska Center for Materials and Nanoscience: Faculty Publications
According to theoretical studies, narrow graphene nanoribbons with atomically precise armchair edges and widths of(1.1 eV), which makes them potentially promising for logic applications. Different top–down fabrication approaches typically yield ribbons with width >10nm and have limited control over their edge structure. Here we demonstrate a novel bottom–up approach that yields gram quantities of high-aspect-ratio graphene nanoribbons, which are only ~1 nm wide and have atomically smooth armchair edges. These ribbons are shown to have a large electronic bandgap of ~1.3 eV, which is significantly higher than any value reported so far in experimental studies of graphene nanoribbons prepared by …
Effect Of Temperature On Tunneling And Quantum Efficiency In Cigs Solar Cells,
2014
New Jersey Institute of Technology
Effect Of Temperature On Tunneling And Quantum Efficiency In Cigs Solar Cells, Sizhan Liu
Theses
Utilizing the two-band approximation and Wentzel-Kramers-B ri l l oui n (WKB) approximation, by including the temperature-dependent effective masses and nonparabolicity effects, an investigation of the temperature dependent band-to-band tunneling process is discussed. In comparison with the parabolic approximation and non- parabolic approximation, the tunneling probability is strongly dependent on the non-parabolicity factor. The temperature dependence of the energy band gap, electron effective mass and light hole effective mass is investigated. The tunneling current density function is derived by a series representation of the incomplete gamma function with non-parabolic effect and its variation at low temperature is also investigated. When …
Analysis Of Transport Properties In A Zaz Graphene Nanoribbon Junction Using Various Dopants,
2014
New Jersey Institute of Technology
Analysis Of Transport Properties In A Zaz Graphene Nanoribbon Junction Using Various Dopants, Natasha Parikh
Theses
A 12 atom wide ZAZ Graphene Junction was simulated and its transport properties were analyzed. I-V curves, calculated by nonequilibrium Greens function method combined with the density functional theory under external bias, showed varying semiconducting characteristics. Further, the width of the junction also showed significant effects in the determination of the semiconducting nature. A theoretical study was performed on the semiconducting characteristics by analyzing the I-V curve and transport coefficients in the junction.
Microstructure And Magnetic Properties Of Bulk Nanocrystalline Mnal,
2014
Dartmouth College
Microstructure And Magnetic Properties Of Bulk Nanocrystalline Mnal, Anurag Chaturvedi, Rumana Yaqub, Ian Baker
Dartmouth Scholarship
MnAl is a promising rare-earth free permanent magnet for technological use. We have examined the effects of consolidation by back-pressure, assisted equal channel angular extrusion processing on mechanically-milled, gas-atomized Mn-46% at. Al powder. X-ray diffraction showed both that the extruded rod consisted mostly of metastable τ phase, with some of the equilibrium γ2 and β phases, and that it largely retained the as-milled nanostructure. Magnetic measurements show a coercivity of ≤4.4 kOe and a magnetization at 10 kOe of ≤40 emu/g. In addition, extrusions exhibit greater than 95% of the theoretical density. This study opens a new window in …
Jamming Rheology Of Model Cementitious Suspensions Composed Of Comb-Polymer Stabilized Magnesium Oxide Particles,
2014
Purdue University
Jamming Rheology Of Model Cementitious Suspensions Composed Of Comb-Polymer Stabilized Magnesium Oxide Particles, Lisa R. Murray, Kendra Erk
School of Materials Engineering Faculty Publications
The colloidal microstructure of concentrated suspensions containing anionic comb- polymer-stabilized magnesium oxide (MgO) particles in water was analyzed by shear rheometry for indications of changes in particle microstructure based on particle size and comb-polymer usage. As the suspensions were sheared at different rates, jamming in the sheared MgO suspensions was observed as shear stress overshoots. The shear-induced evolution of the suspension’s microstructure was strongly related to the perceived interactions between neighboring MgO particles in the suspension. In the jammed state, interactions are believed to be enhanced by the formation of entanglements between opposing comb-polymer side-chains. Steric repulsion between side-chains was …
Dynamical Heterogeneity In Periodically Deformed Polymer Glasses,
2014
Wright State University - Main Campus
Dynamical Heterogeneity In Periodically Deformed Polymer Glasses, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The dynamics of structural relaxation in a model polymer glass subject to spatially homogeneous, time-periodic shear deformation is investigated using molecular dynamics simulations. We study a coarse-grained bead-spring model of short polymer chains below the glass transition temperature. It is found that at small strain amplitudes, the segmental dynamics is nearly reversible over about 104 cycles, while at strain amplitudes above a few percent, polymer chains become fully relaxed after a hundred cycles. At the critical strain amplitude, the transition from slow to fast relaxation dynamics is associated with the largest number of dynamically correlated monomers as indicated by the …
Electronic Properties Of Inp (001)/Hfo2 (001) Interface: Band Offsets And Oxygen Dependence,
2014
San Jose State University
Electronic Properties Of Inp (001)/Hfo2 (001) Interface: Band Offsets And Oxygen Dependence, Santosh Kc
Faculty Publications
Using ab-initio methods, atomic structures and electronic properties of InP (001)/HfO2 (001) interface are studied within the framework of density functional theory. We examine the InP/HfO2 model interface electronic structures under varying oxidation conditions. The effects of indium and phosphorous concentrations on interfacial bonding, defect states, band offsets, and the thermodynamic stability at the interface are also investigated. The origin of interfacial gap states in InP (001)/HfO2 (001) interface are proposed, mainly from the P-rich oxides, which is validated by our experimental work. This highlights the importance of surface passivation prior to high-κ deposition based on the in situ spectroscopic …
Development Of Precipitation Hardenable Al-Sc-Zr-Hf Quaternary Alloys Through Thermodynamic Modeling, And Room-Temperature And Elevated Temperature Hardness,
2014
Michigan Technological University
Development Of Precipitation Hardenable Al-Sc-Zr-Hf Quaternary Alloys Through Thermodynamic Modeling, And Room-Temperature And Elevated Temperature Hardness, Matthew J. Wong
Dissertations, Master's Theses and Master's Reports - Open
Aluminum alloyed with small atomic fractions of Sc, Zr, and Hf has been shown to exhibit high temperature microstructural stability that may improve high temperature mechanical behavior. These quaternary alloys were designed using thermodynamic modeling to increase the volume fraction of precipitated tri-aluminide phases to improve thermal stability. When aged during a multi-step, isochronal heat treatment, two compositions showed a secondary room-temperature hardness peak up to 700 MPa at 450°C. Elevated temperature hardness profiles also indicated an increase in hardness from 200-300°C, attributed to the precipitation of Al3Sc, however, no secondary hardness response was observed from the Al …
