Engineering Science and Materials Commons^™

Preparation And Performance Of The Thin-Film Libpon Electrolyte, Feng Wu, Ya-Dong Liu, Ren-Jie Chen, Shi Chen

Journal of Electrochemistry

The LiBPON thin-film electrolyte was prepared by magnetron sputtering,and the relationship between the performance and the deposition condition was investigated.As seen in the SEM images,the thin films are dense and uniform without cracks,and according to the XRD patterns they have an amorphous structure.The electrochemical performance of the electrolyte was characterized by electrochemical impedance spectroscopy(EIS).The ionic conductivities of the thin film decreased with the RF power,but increased with the N₂ pressure.The an ionic conductivity of 3.5×10^-6 S/cm at room temperature was found from the electrochemical measurement.While the deposition rate increased with the RF power,but decreased with the N_{2 …}

Hydrothermal Preparation And Electrochemical Characterizations Of Vanadate Compound Nav2O5 Crystals, Fang Hu, Xing Ming, Fei Du, Ying-Jin Wei, Gang Chen, Chun-Zhong Wang

Journal of Electrochemistry

The NaV₂O₅ was prepared by a low temperature hydrothermal process. The material crystallized in the layered orthorhombic structure with space group Pmmn. X-ray diffraction confirmed that the material was pure and the scanning electron microscopy showed that the material was composed of needle crystals with 20 μm in length and 200 nm in width. X-ray photoelectron spectroscopy indicated the co-existence of V⁴⁺ and V⁵⁺ in the material,which results in an average V^4.5+ oxidation state of the material. The observed Raman bands were ascribed to different V-O vibrations. The first specific capacity about 120 mAh/g …

Photoelectrochemical Properties Of Tio2 Nanoparticles, Jie Qu, Ying Li, Qi-Wei Jiang, Xue-Ping Gao

Journal of Electrochemistry

The protonated titanate nanoparticles were obtained at room temperature and subsequently calcined at different temperatures(300 ℃,400 ℃,500 ℃,600 ℃ and 700 ℃) in air.The obtained products were characterized by XRD,TEM and UV-Vis.It is found that the grain sizes of TiO₂ nanoparticles calcined at 300 ℃ were about 20 nm,and increased gradually with the temperature rise.Photoelectric performance was measured with I～V curve and electrochemical impedance spectroscopy(EIS).The TiO₂ nanoparticles obtained at 500 ℃ showed the best photoelectrochemical properties with a photovoltaic conversion efficiency of 6.39%,which is much higher than those at other temperatures.In addition,it is also demonstrated that the charge …

Electrooxidation Behaviors Of Tib2 As High Capacity Anodic Material In Neutral Aqueous Electrolytes, Ya-Dong Wang, Xian-Yong Guang, Zhi-Xin Wang, Xin-Ping Ai, Han-Xi Yang

Journal of Electrochemistry

Titanium diborides were investigated as an anodic material for neutral aqueous batteries. It is revealed that this material shows superiorly high electrochemical activities in the neutral electrolytes. The discharge capacities observed for TiB₂ reached 1300 mAh/g at the constant current density of 50 mA/g, exceeding all the metal electrodes reported so far. The electrooxidation of this compound was found to proceed via the electrochemical dissolution of boron to form borofluoride, while titanium remained unchanged at the electrode. These results suggest a possible use of the boride compounds as a new material for constructing neutral aqueous batteries with high electrochemical …

The Electrochemical Performance Of Ncf-Sulfur Cathode, Chun-Rong Zhao, Zhong-Bao Yu, Wei-Kun Wang, Yu-Sheng Yang

Journal of Electrochemistry

The electrochemical performance of NCF-sulfur cathode, with different NCF contents, was investigated by constant current discharge, cyclic voltammetry and AC impedance methods. The morphologies of the cathodes were observed using scanning electron microscopy. The results indicate that the cycle life and rate capability of NCF-sulfur cathode increased. Better performance of sulfur cathode was obtained by 3% and 5% NCF conductive addition. When the current density was 0.4 mA/cm², the 3% NCF-sulfur cathode had an initial capacity of 880 mAh/g and a reversible capacity of 630 mAh/g after 20 cycles.

Preparation And Characterization Of Tin-Nickel Alloy Electromagnetic Shielding Fabric, Ke-Jing Chu, Wei Wang, Bin Sun, Mei-Fang Zhu

Journal of Electrochemistry

A soft electromagnetic shielding fabric was successfully prepared by electroplating tin-nickel alloy on the Cu-plated PET fabric in potassium pyrophosphate system. Results show that the different tin content and different colour can be obtained by changing the ratio of metals in bath. Better corrosion resistance and anti-tarnishing were achieved with the fabric consisting of 68.96% Sn. The tin-nickel alloy surface for the electromagnetic shielding fabric had excellent conductivity, softness, permeability and soft luster, non-sensitized to the human body. Thereby it has broad prospect in EMI field and shielding clothing.

Electrosynthesis Of 2,2-Dimethylolpropionic Acid, Hong-Yan Sun, Zhen-Hai Liang

Journal of Electrochemistry

The Ti/SnO₂+Sb₂O₄/PbO₂ electrode was prepared.The structure phase and valent state were characterized by means of XRD and XPS.The 2,2-dimethylolpropionic acid was synthesized on the Ti/SnO₂+Sb₂O₄/PbO₂ anode by direct electro-oxidation of 2,2-dimethylolpropionaldehyde.The product and crude material were analyzed by HPLC,the effects of the concentration of 2,2-dimethylolpropionaldehyde,pH,potential and reaction temperature were studied.The results showed that the optimum conditions were anode potential 1.8 V,pH=1,reaction temperature 15 ℃ and 2,2-dimethylolpropionaldehyde concentration 0.10mol/L.Under the optimum conditions,the selectivity of 36%,the current efficiency of 28% and the conversion of 58% were reached.The reported …

The Electrochemical Behavior And Determination Of Carbendazim On Iron Montmorillonite Modified Electrode, Xiao-Li Jiang, Rong Li, Xiao-Ying He, Jiang Li, Ying Li

Journal of Electrochemistry

The FeCl₃ modified clay electrode was made.The electrochemical behavior of carbendazim(BCM) on the modified electrode was studied by cyclic voltammetry.The impacts of pH,scan rate and dosages of modifier were discussed and the important kinetic parameters of the electrochemical process were determined.The results indicated that the process was controlled by diffusion.The effective area of FeMM-CMC/GCE(A)=0.027 cm²,the transfer electron numbers(n)=2 and the diffusion coefficient(D)=5.115×10^-6cm²/s.Under the optimized conditions,a good linearity was found between the first order derivative of peak current and concentration of BCM in the range of 2.00×10^-5～8.00×10^-4mol/L,with i′p=-8.045×10^-7-0.0237c,correlation …

Synthesis,Characteristics And Electrochemical Performance Of Nano-Sized Snco/Graphite Composites As Anode For Lithium Ion Batteries, Jin-Shu Cai, Ling Huang, Fu-Sheng Ke, Shi-Gang Sun

Journal of Electrochemistry

The nano-structural Sn-Co/graphite composites were prepared by chemical reduction of the alloy electroless deposition solution in graphite suspensions, and the composites were annealed at 500 ℃. The phase structure and surface morphology of the composites were measured by XRD, SEM and Raman. The results indicate that there were high dispersions and high loadings of Sn-Co nanoparticles on graphite by thermal treatment. Electrochemical lithium storage performance was studied preliminarily on the obtained samples. The graphite modified with the Sn-Co nanoparticles possessed a higher electrochemical reversible capacity than that of graphite during the charge and discharge process. The appetency between the Sn-Co …

High Utilization Aupt Nanoparticles Supported On Mwcnts For Methanol Electro-Oxidation In Alkaline Medium, Xun Guo, Dao-Jun Guo, Xin-Ping Qiu, Li-Quan Chen, Wen-Tao Zhu

Journal of Electrochemistry

We synthesized gold-platinum electrocatalysts supported on multi-walled carbon nanotubes(MWCNTs) with high utilization by a simple one-step method.A high Pt loading series of bimetallic AuPt/MWCNTs catalysts were prepared by the improved ethylene glycol reduction method,and then were compared in terms of the electrocatalytic activity for methanol electro-oxidation using cyclic voltammetry(CV) and chronoamperometry in alkaline solutions.The structure of AuPt/MWCNTs was characterized by the transmission electron microscopy(TEM),X-ray diffraction(XRD) and energy-dispersive X-ray spectroscopy(EDS).The results showed that the AuPt/MWCNTs catalysts had high Pt utilization,uniform AuPt nanoparticles size and good electrocatalytic activity for methanol electro-oxidation.The effect of Au/Pt mass ratio on electrocatalytic activity was also investigated.The …

Characterization Of A Viscoelastic Response From Thin Metal Films Deposited On Silicon For Microsystem Applications, Steven L. Meredith

Master's Theses

Understanding the mechanisms that control the mechanical behavior of microscale actuators is necessary to design an actuator that responds to an applied actuation force with the desired behavior. Micro actuators which employ a diaphragm supported by torsional hinges which deform during actuation are used in many applications where device stability and reliability are critical. The material response to the stress developed within the hinge during actuation controls how the actuator will respond to the actuating force. A fully recoverable non-linear viscoelastic response has been observed in electrostatically driven micro actuators employing torsional hinges of silicon covered with thin metal films. …

Integrated Bipolar Plate - Gas Diffusion Layer Design For Polymer Electrolyte Membrane Fuel Cells, David N. Neff

Browse all Theses and Dissertations

Bipolar plates compose a large portion of the weight and manufacturing costs in fuel cells. Bipolar plates are metal plates that separate each membrane-electrode assembly in a fuel cell stack. They provide structural strength, contain flow channels for fuel transport, and conduct electricity in the fuel cell. Electricity also flows through the gas diffusion layer (GDL) which lies next to the bipolar plate. Because the GDL is separate from the bipolar plate, there is a contact resistance as the electricity flows from one to the other. The scope of this thesis is to research an efficient way of manufacturing a …

Towards Blended Learning For Deaf Studies At Third Level In Ireland,, Brian Nolan, Lorraine Leeson, John Bosco Conama

Conference Papers

Irish Sign Language (ISL), an indigenous language of Ireland, is recognized by the EU as a natural language. It is a language seperate from the other languages used in Ireland, including English, Irish, and, in Northern Ireland.

The Investigation Of Nano Silica In The Cement Hydration Pro, Jonathan Samuel Belkowitz

Electronic Theses and Dissertations

With the advent of nano technology, materials have been developed that can be applied to high performance concrete mix designs. Nano silica reacts with calcium hydroxide (CH) to develop more of the strength carrying structure of cement: calcium silica hydrate (CSH). In this paper, relationships have been developed to distinguish the benefits when using different sizes of nano silica in cement paste. An extensive regime of experimental analysis was carried out to determine the effect of nano silica. Through these experiments the heat of hydration of multiple cement mix designs was measured. After that, the concentration of CH was recorded …

Design Of Sea Water Heat Exchanger For Miniature Vapor Compression Cycle, James Hughes

Electronic Theses and Dissertations

Recent advances in the development of miniature vapor compression cycle components have created unique opportunities for heating and cooling applications, specifically to human physiological requirements that arise in extreme environments. Diving in very cold water between 1.7 and 5°C requires active heating because passive thermal insulation has proven inadequate for long durations. To maintain diver mobility and cognitive performance, it is desirable to provide 250 to 300 W of heat from an untethered power source. The use of a miniature vapor compression cycle reduces the amount of power (batteries or fuel cell) that the diver must carry by 2.5 times …

Droplet Flows In Microchannels Using Lattice Boltzmann Method, Amit Gupta

Electronic Theses and Dissertations

Microelectromechanical systems (MEMS) have widespread applications in medical, electronical and mechanical devices. These devices are characterized by the smallest dimension which is at least one micrometer and utmost one millimeter. Rapid progress in the manufacture and utilization of these microdevices has been achieved in the last decade. Current manufacturing techniques of such devices and channels include surface silicon micromachining; bulk silicon micromachining; lithography; electrodeposition and plastic molding; and electrodischarge machining (EDM). In recent years, electrostatic, magnetic, electromagnetic and thermal actuators, valves, gears and diaphragms of dimensions of hundred microns or less have been fabricated successfully. Sensors have been manufactured that …

Study Of The Effects Of Sodium And Absorber Microstructure For The Development Of Cuin1-Xgaxse2-Ysy Thin Film Solar Cell Using An Alternative Selenium Precursor, Vinaykumar Hadagali

Electronic Theses and Dissertations

Thin film solar cells have the potential to be an important contributor to the world energy demand in the 21st century. CuInGaSe2 thin film solar cells have achieved the highest efficiency among all the thin film technologies. A steady progress has been made in the research and development of CuInSe2 based thin film solar cells. However, there are many issues that need to be addressed for the development of CuInSe2 based thin films solar cells. High price of PV modules has been a biggest factor impeding the growth of photovoltaic modules for terrestrial application. This thesis tries to address the …

Identification Of Multiple Oscillation States Of Carbon Nanotube Tipped Cantilevers Interacting With Surfaces In Dynamic Atomic Force Microscopy, Mark Strus, Arvind Raman

Birck and NCN Publications

Carbon nanotubes (CNTs) have gained increased interest in dynamic atomic force microscopy (dAFM) as sharp, flexible, conducting, nonreactive tips for high-resolution imaging, oxidation lithography, and electrostatic force microscopy. By means of theory and experiments we lay out a map of several distinct tapping mode AFM oscillation states for CNT tipped AFM cantilevers: namely, noncontact attractive regime oscillation, intermittent contact with CNT slipping or pinning, or permanent contact with the CNT in point or line contact with the surface while the cantilever oscillates with large amplitude. Each state represents fundamentally different origins of CNT-surface interactions, CNT tip-substrate dissipation, and phase contrast …

Computational Model For Predicting Nonlinear Viscoelastic Damage Evolution In Materials Subjected To Dynamic Loading, Flavio V. Souza, Yong-Rak Kim, George A. Gazonas, David H. Allen

Department of Mechanical and Materials Engineering: Faculty Publications

Many inelastic solids accumulate numerous cracks before failure due to impact loading, thus rendering any exact solution of the IBVP untenable. It is therefore useful to construct computational models that can accurately predict the evolution of damage during actual impact/dynamic events in order to develop design tools for assessing performance characteristics. This paper presents a computational model for predicting the evolution of cracking in structures subjected to dynamic loading. Fracture is modeled via a nonlinear viscoelastic cohesive zone model. Two example problems are shown: one for model validation through comparison with a one-dimensional analytical solution for dynamic viscoelastic debonding, and …

Experimental Study Of The Response Of Semiconductor Detectors For Edxrf Analysis., Sunil Kumar Valaparla

Open Access Theses & Dissertations

This present work relates to the study and characterization of the response function of an energy-dispersive x-ray spectrometer. The problems of energy, efficiency and resolution calibration of the system operating in the energy (5-60 keV) range are discussed. We present the operation characteristics of the portable pyro-electric x-ray generator (COOL-X) and the application of the calibrated response spectrum in the elemental analysis using X-ray Fluorescence (XRF).

We study the response of the Si(Li)-Pin XR-100CR semiconductor detector to low energy photons. The photopeak efficiency was determined experimentally by using radioisotopes and compared against a theoretical efficiency curve. The efficiency for gamma …

Effects Of Aggregate Structure On Hot-Mix Asphalt Rutting Performance In Low Traffic Volume Local Pavements, Yong-Rak Kim, Hee Mun Park, Francisco Thiago Sacramento Aragão, Jamilla Emi Sudo Lutif

Department of Mechanical and Materials Engineering: Faculty Publications

The objective of this study is to evaluate the effect of mix gradations associated with the Superpave restricted zone on rutting potential specifically for low traffic volume roadways. Although the elim-ination of the restricted zone requirement in Superpave mix design is highly recommended, some questions still remain unanswered as the research conclusions supporting the elimination of the re-stricted zone were largely made for medium to high traffic volume roadways, where aggregates are highly crushed and of good quality. The applicability of such research conclusions based on high traffic volume mixes needs to be verified for low volume mixes because many …

Characterization And Cytotoxic Assessment Of Ballistic Aerosolized Particulates For Tungsten Alloy Penetrators Interacting With Steel Targets, Brenda Ivette Machado

Open Access Theses & Dissertations

The aerosolized particulates produced during an impact of depleted uranium munitions can potentially contaminate extensive areas around the impact sites and cause a wide spectrum of civilian and military damage. Thus materials such as WHA have been prompted for consideration. The present research is concerned with the regular collection of aerosol particulates associated with ballistic WHA rod penetration into rolled homogeneous steel (RHA) or other related steel armor as armor plate sequences. Particulate size characterization via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) along with chemical compositions via energy dispersive spectroscopy (EDS) were the focus of this research. …

Fabrication And Characterization Of Zirconium Oxide Thin Films, Vemnkata Rama Sesha Ravi Kumar Vemuri

Open Access Theses & Dissertations

Zirconium oxide (ZrO2) is an important material with a potential for a wide range of technological applications. The outstanding chemical stability, electrical and mechanical properties, high dielectric constant, and wide band gap of ZrO2 make it suitable for several industrial applications in the field of optics, electronics, magneto-electronics, and optoelectronics. ZrO2 is frequently used as a high refractive index material in multilayer optical coatings in high power laser systems. ZrO2 is employed in super plastic structural ceramics that demonstrate excellent strength and fracture toughness. ZrO2 has been considered as a promising dielectric to replace SiO2 in advanced metal oxide semiconductor …

Effect Of Sodium And Absorber Thickness On Cigs2 Thin Film Solar Cells, Parag Vasekar

Electronic Theses and Dissertations

Chalcopyrites are important contenders among solar cell technologies due to direct band gap and higher absorption coefficient. CuIn1-xGaxS2 (CIGS2) thin-film solar cells are of interest for space power applications because of near optimum bandgap of 1.5 eV for AM0 solar radiation outside the earth's atmosphere. The record efficiency of 11.99% has been achieved on a 2.7 µm CIGS2 thin film prepared by sulfurization at FSEC PV Materials Laboratory. Since CIGS2 films are typically grown in copper-rich regime, excess cuprous sulfide which helps in the formation of CIGS2 is etched away. This makes CIGS2 nearly stoichiometric. However, it is difficult to …

Volume Viscosity In Fluids With Multiple Dissipative Processes, Allan J. Zuckerwar, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

The variational principle of Hamilton is applied to derive the volume viscosity coefficients of a reacting fluid with multiple dissipative processes. The procedure, as in the case of a single dissipative process, yields two dissipative terms in the Navier-Stokes equation: The first is the traditional volume viscosity term, proportional to the dilatational component of the velocity; the second term is proportional to the material time derivative of the pressure gradient. Each dissipative process is assumed to be independent of the others. In a fluid comprising a single constituent with multiple relaxation processes, the relaxation times of the multiple processes are …

Enhancing Reductive Dechlorination Of Chlorinated Ethenes And Ethanes In A Natural Treatment System, Caroline Burda

LSU Master's Theses

Chlorinated solvent contamination continues to plague sites around the world. In many cases, lower chlorinated daughter products build up and remain in ground waters and soils. A Bio-Filter/Phytobed (BFP) system has been developed to replace a traditional pump and treat technology currently operating at the ReSolve Superfund site in North Dartmouth, MA. Pilot scale testing at the facility displayed a significant acclimation period prior to microbial dechlorination, as well as delayed degradation of chlorinated ethanes. Microcosm studies suggest that acidic conditions, possibly created by the peat mixture used to construct the bio-filter, inhibited bacterial growth. The neutralization of trench pH …

Development And Thermal Characterization Of Cellulose/Clay Nanocomposites, Christopher D. Delhom

LSU Master's Theses

Cotton is the most important textile fiber for apparel use and is preferred to synthetic fibers for reasons such as comfort and feel. Cotton may also be used to produce the regenerated cellulose fibers, such as lyocell and viscose, which have numerous textile applications. A major drawback of cotton, and other cellulosic fibers, is its inherent ability to burn. Many finishes have been developed to impart flame resistance to cotton. These finishes have limited use in textiles for apparel due to problems with the finish not being durable during laundering and increasing the susceptibility of the fabric to wear. Most …

Charge Induced Enhancement Of Adsorption For Hydrogen Storage Materials, Xiang Sun

Dissertations, Master's Theses and Master's Reports - Open

The rising concerns about environmental pollution and global warming have facilitated research interest in hydrogen energy as an alternative energy source. To apply hydrogen for transportations, several issues have to be solved, within which hydrogen storage is the most critical problem. Lots of materials and devices have been developed; however, none is able to meet the DOE storage target. The primary issue for hydrogen physisorption is a weak interaction between hydrogen and the surface of solid materials, resulting negligible adsorption at room temperature. To solve this issue, there is a need to increase the interaction between the hydrogen molecules and …

Understanding Practical Limits To Heavy Truck Drag Reduction, Drew Landman, Richard Wood, Whitney Seay, John Bledsoe

Mechanical & Aerospace Engineering Faculty Publications

A heavy truck wind tunnel test program is currently underway at the Langley Full Scale Tunnel (LFST). Seven passive drag reducing device configurations have been evaluated on a heavy truck model with the objective of understanding the practical limits to drag reduction achievable on a modern tractor trailer through add-on devices. The configurations tested include side skirts of varying length, a full gap seal, and tapered rear panels. All configurations were evaluated over a nominal 15 degree yaw sweep to establish wind averaged drag coefficients over a broad speed range using SAE J1252. The tests were conducted by first quantifying …

Art In A New Light: Design And Assessment Of Illuminants To Reduce Photochemical Degradation Of Works Of Art, Monica Fabiola Delgado

Open Access Theses & Dissertations

The purpose of this research is to design the best lighting that will minimize long term photochemical degradation of Old Master Drawings and/or other works of art, while maintaining the patron's appreciation of the object's color and detail. The present approach is a technological refinement to the basic underlying earlier work on fluorescent lighting by W. A. Thornton, W.A. at General Electric1. Thin-film dielectric, multi-coating technology is used to create filters that eliminate ultraviolet light, near infrared light and significant unnecessary parts from the visible spectrum, thus maximizing the reduction in photochemical degradation, while maintaining optimal color rendering. Three interference …