bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Multilayer Anodes for SOFC
Authors: Müller Axel C. , Krügel Albert , Weber André , Ivers-Tiffée Ellen 
Published: April 2011

ABSTRACTSOFC anodes have to combine various tasks. In anode supported single cells a thick anode substrate is used for current collecting and gas distribution whereas a thin functional layer adjacent to the electrolyte is the electrochemically active part of the anode. This functional anode layer is cofired together with the thin film electrolyte to obtain an enhanced interface with low polarisation losses. This multilayer structure was transferred to an electrolyte supported single cell. The electrochemical active Ni/8YSZ anode layer was screen printed onto a 8YSZ electrolyte green tape and subsequently cofired at 1350 °. Mechanical stresses during cofiring due to shrinkage mismatch of anode and electrolyte were avoided by changing the geometry of the anode layer from a continuous layer to a large number of small sized individual areas. Simulations by finite element modeling indicated that a hexagonal pattern similar to honeycombs is preferable. The second layer which adjoins to the fuel gas channels and which is responsible for current collecting and gas distribution was later on screen printed on top and sintered together with the cathode. Single cells with a multilayer anode and different functional layers were electrochemically characterised under realistic operation conditions. The performance and reduction/oxidation stability of this type of anode was investigated. The electrochemically active layer showed only small degradation during redox cycling and long term operation at high fuel utilisation. In contradiction to single layer anodes Nickel agglomeration was not observed in the functional layer.
Characterization of Polymer Clay Nanocomposite Electrolyte Motions via Combined NMR and Neutron Scattering Studies
Authors: Smith Luis J. , Zanotti Jean-Marc , Sandi Giselle , Carrado Kathleen A. , Porion Patrice , Delville Alfred , Price David L. , Saboungi Marie-Louise 
Published: April 2011

ABSTRACTThe activation energies for poly(ethylene oxide) motion in a polymer clay composite are reported for the polymer intercalated and external to the clay. PEO intercalated into the clay is found to have a lower activation energy for motion but also a larger Arrhenius prefactor, by almost two orders of magnitude, than for PEO found external to the clay. Neutron scattering measurements confirm the presence of two environments and the effects of confinement on the mean square displacement of the PEO.
Crystal Chemistry of Chemically Delithiated Layered Oxide Cathodes of Lithium Ion Batteries
Authors: Manthiram A. , Venkatraman S. 
Published: April 2011

ABSTRACTThe structural and chemical stabilities of layered Li1-xCoO2-δ, Li1-xNi0.85Co0.15O2-δ and Li1-xNi0.5Mn0.5O2-δ (0 ≤ (1-x) ≤ 1) cathodes have been investigated by chemically extracting lithium from the corresponding LiMO2 with the oxidizer NO2BF4 in acetonitrile medium. While Li1-xCoO2-δ and Li1-xNi0.85Co0.15O2-δ begin to form a P3-type and a new O3-type (designated as O3') phases, respectively, for (1-x) < 0.5 and (1-x) < 0.3, Li1-xNi0.5Mn0.5O2-δ maintains the initial O3-type structure without forming any second phase. Chemical analysis with a redox titration indicates that the Li1-xCoO2-δ, Li1-xNi0.85Co0.15O2-δ, and Li1-xNi0.5Mn0.5O2-δ systems begin to lose oxygen from the lattice, respectively, for (1-x) < 0.5, < 0.3 and < 0.4, which is accompanied by an onset of a decrease in the c parameter. The oxygen loss signals chemical instability and the trend in instability correlates with the charging voltage profiles of the cathodes.
Carbon Coated Silicon Powders As Anode Materials For Lithium Ion Batteries
Authors: Gulbinska M. , Galasso F. S. , Suib S. L. , Iaconetti S. , Russell P. G. , DiCarlo J. F. 
Published: April 2011

ABSTRACTNovel lithium ion battery anode materials consisting of carbon-coated silicon were prepared. Chemical vapor deposition (CVD) methods were used in the syntheses of these composite materials with toluene being used as the precursor for carbon coatings on silicon powder. The temperature of carbon deposition was 950°C and the deposition time was 30 min for powdered substrates. Carbon-coated silicon powders were analyzed by HRSEM, TEM, and Raman spectroscopy. Coin cells were made and cycled to evaluate the electrochemical performance of carbon-coated silicon powders. Coated materials performed well during the initial coin cell testing. Silicon wafers (orientation <111>) were also used as the substrates for carbon coatings. Silicon wafers were coated for 40 seconds at 950°C. Auger spectroscopy and XPS depth profiling were used to analyze the thin films of toluene-derived carbons on silicon wafers.
Synthesis and Electrochemical Behaviour of Ramsdellite LiCrTiO4
Authors: García-Alvarado F. , Martín-Gil M. , Kuhn A. 
Published: April 2011

ABSTRACTA ramsdellite with composition LiCrTiO4 has been obtained by heating the spinel of same composition to high temperature. The new ramsdellite has been investigated in view of its possible use as an electrode material in lithium rechargeable batteries. Lithium can be partially extracted from ramsdellite LiCrTiO4 and further intercalated into, by contrast to the spinel of same composition. The average operating voltage during lithium extraction is 4 Volts vs. lithium, and the process produces a specific capacity of 90 mAh/g at 0.1 mA/cm2. On the other hand, upon reduction from open circuit voltage, lithium can be reversibly intercalated into the ramsdellite polymorph at ca. 1.5 V vs. lithium yielding a rechargeable capacity of 110 mAh/g at 0.1 mA/cm2.
Kinetics of Oxygen Exchange in Sr(Ti0.65Fe0.35)O3
Authors: Schneider Th. , Wagner S. F. , Menesklou W. , Ivers-Tiffée E. 
Published: April 2011

ABSTRACTCurrent limiting electrochemical pumping cells (amperometric sensors) based on zirconia are commonly used for engine control applications. Fast resistive-type sensors adapted from semiconducting metal oxides are a promising alternative for future exhaust gas monitoring systems. Therefore among the interesting characteristics of the materials system Sr(Ti0.65Fe0.35)O3, including high sensitivity and temperature independence at high oxygen partial pressures (pO2 > 10-4 bar), a short response time (t90 = 30 ms) is obviously the most salient.The latter is determined by the kinetics of the oxygen surface transfer and subsequent diffusion of oxygen vacancies V‥O. For thin samples and low temperatures the surface transfer is dominant, since bulk diffusion usually occurs very fast. The presented model is based on the frequency-domain analysis of amplitude and phase shift of the response signal obtained from a pO2 modulation in a fast kinetic measurement setup. This method allows both the measurement of response times in the sub-millisecond range as well as the distinction of the behaviour either controlled by volume diffusion or by surface transfer reaction in Sr(Ti0.65Fe0.35)O3 ceramics.
The Effect of Composition on the Wetting Behavior and Joint Strength of the Ag-CuO Reactive Air Braze
Authors: Scott Weil K. , Coyle Chris A. , Kim Jin Yong , Hardy John S. 
Published: April 2011

ABSTRACTAs interest in high temperature electrochemical membrane devices for energy and gas generation has intensified, it has become apparent that developing an appropriate method of hermetically joining the ceramic and metallic components in these devices will be critical to their success. A recently developed technique referred to as reactive air brazing (RAB) has shown promise in the joining of components for planar solid oxide fuel cells (pSOFC) and oxygen generators. In the study described below, the relationship between braze composition, substrate wetting, and joint strenth was investigated to gain further understanding of the RAB process. It was found that braze wettability and joint strength are inversely related for the simple binary Ag-CuO braze system.
Optimization of the sintering of Aurivillius phases using D-optimal statistical design
Authors: Peterson M.S. , Misture S.T. 
Published: April 2011

ABSTRACTA statistical model has been employed to determine the optimal sintering times and temperatures for Bi2Sr2Nb2TiO12. The phase of interest was made in pure form by solid-state synthesis. Bi2O3 was used as a sintering aid to decrease sintering temperatures and increase densification. The amount of Bi2O3 added and the sintering temperature had a statistical impact on density, while the heat treatment time did not.
Ultra CO Tolerant PtMo/PtRu anodes for PEMFCs
Authors: Ball Sarah C , Thompsett David 
Published: April 2011

ABSTRACTProgress has been made in designing an anode electrode that can tolerate CO levels of several thousand ppm which are a typical output of a fuel processor consisting of a reformer and water-gas-shift unit only. The combination of a PtMo catalyst that is capable of electrochemically oxidising CO and a PtRu catalyst that can tolerate high levels of CO2 arranged in a bilayer configuration, has been shown to tolerate 2000 ppm CO in H2 with a relatively small loss in fuel cell performance. Further improvements in the ability to tolerate higher levels of CO with lower performance losses are expected due to improved PtMo catalyst design.
Fuel Cell Applications of Nanotube-Metal Supported Catalysts
Authors: Gennett T. , Landi B. J. , Elich J. M. , Jones K. M. , Alleman J. L. , Lamarre P. , Morris R. S. , Raffaelle R. P. , Heben M.J. 
Published: April 2011

ABSTRACTNovel carbon materials with nanometer dimensions are of potentially significant importance for a number of advanced technological applications. Within this report we describe the results for the electrochemical characterization of a series of single walled carbon nanotube (SWNT) metal supported catalysts as cathodes for basic fuel cell systems. Compared to the typical carbon black electrocatalysts, the nanotube supported platinum catalyst resulted in up to a 140% improvement in the efficiency for a proton exchange membrane (PEM) fuel cell.
The Effect of the Nano and Microstructure of PtRu/C Electrocatalysts Towards Methanol and Carbon Monoxide Oxidation
Authors: Sugimoto Wataru , Kawaguchi Tomoyuki , Murakami Yasushi , Takasu Yoshio 
Published: April 2011

ABSTRACTNanoparticul ate Pt50Ru50 supported on a carbon black (CB) were prepared by an impregnation method and the effect of the nano and microstructure towards the electrocatalytic oxidation of methanol and carbon monoxide were evaluated. The in-house prepared PtRu nanoparticles were well-alloyed and finely dispersed on CB, as revealed by XRD and FESEM. FESTEM-EDX analysis of isolated PtRu single nanoparticles indicated that although the majority of the binary particles had a metal composition in accordance to the nominal ratio, some compositional deviation was observed. The activity towards electrocatalytic oxidation of methanol and preadsorbed carbon monoxide is discussed based on the nano and microstructure.
Bipolar Plate-Supported Solid Oxide Fuel Cells for Auxiliary Power Units
Authors: David Carter J. , Cruse Terry A. , Bae Joong-Myeon , Ralph James M. , Myers Deborah J. , Kumar Romesh , Krumpelt Michael 
Published: April 2011

ABSTRACTThis paper presents an advanced design and fabrication concept for a solid oxide fuel cell (SOFC). The concept is based on a laminate repeat unit comprised of a thin electrolyte, cermet anode, metallic gas flow fields, and a metallic bipolar plate. The laminate is sintered in a singlestep process in a controlled atmosphere, and the cathode is applied and sintered in situ during the initial heating of the cell (or stack). Observations about the types of cracks that formed in the electrolyte during the sintering process guided the development of the sintering protocol to yield the desired product. Cells with power densities exceeding 250 mW/cm2 have been tested.
Study of Ammonia Formation During The Autothermal Reforming of Hydrocarbon Based Fuels
Authors: Khan A.R. , Zhao James , Polevaya O. Y. 
Published: April 2011

ABSTRACTAmmonia formation in autothermal reforming process was studied in Nuvera's Modular Pressurized Flow Reactor facility. Experiments were conducted to study and compare different catalysts for their ammonia formation characteristics. Different hydrocarbon fuels were reformed and effects of fuel structure and operating conditions on ammonia formation were investigated. Reformate generated was analyzed for ammonia contamination by using FTIR spectroscopy.
Microemulsion-Templated Synthesis of Highly Active High-Temperature Stable Partial Oxidation Catalysts
Authors: Kirchhoff Mark , Specht Ullrich , Veser Götz 
Published: April 2011

ABSTRACTHighly active catalysts for high-temperature partial oxidation reactions have been synthesized based on a microemulsion-templated sol-gel synthesis. The catalysts were tested with the direct catalytic oxidation of methane to synthesis gas and showed excellent selectitivites towards syngas combined with very high activity and low ignition temperatures. Furthermore, a surprisingly high long term stability was observed at these high-temperature conditions of T > 900°C. The catalyst therefore seem very promising candidates for high-temperature partial oxidation and hydrogen production from hydrocarbon fuels.
Miniature Fuel Processors for Portable Fuel Cell Power Supplies
Authors: Holladay Jamie , Jones Evan , Palo Daniel R. , Phelps Max , Chin Ya-Huei , Dagle Robert , Hu Jianli , Wang Yong , Baker Ed 
Published: April 2011

ABSTRACTMiniature and microscale fuel processors that incorporate novel catalysts and microtechnology-based designs are discussed. The novel catalyst allows for methanol reforming at high gas hourly space velocities of 50,000 hr-1 or higher while maintaining a carbon monoxide levels at 1% or less. The microtechnology-based designs extremely compact and lightweight devices. The miniature fuel processors, with a volume less than 25 cm3, a mass less than 200 grams, and thermal efficiencies of up to 83%, nominally provide 25 to 50 watts equivalent of hydrogen, which is ample for the portable power supplies described here. With reasonable assumptions on fuel cell efficiencies, anode gas and water management, parasitic power loss, the energy density was estimated at 1700 Whr/kg. These processors have been demonstrated with a CO cleanup method and a fuel cell stack. The microscale fuel processors, with a volume of less than 0.25 cm3 and a mass of less than 1 gram, are designed to provide up to 0.3 watt equivalent of power with efficiencies over 20%.
Model Simulation of Powder Compaction by Complex Mold Based on Deformation Behavior of Free Particles Measured by Compression Test
Authors: Hashimoto Hitoshi , Sun Zheng Ming , Park Yong Ho , Abe Toshihiko 
Published: April 2011

ABSTRACTDiscrete element method (DEM) is one of the excellent procedures for model simulation of behavior of granular assemblies. A two-dimensional DEM simulation of powder compaction by a complex mold was conducted by considering the deformation behavior of individual particles measured by a compression test of free particles. Spherical copper particles were used as a model material in this study. The particles (particle size ranges from 38 to 125microns) were individually compressed between parallel platens to measure compressive load and displacement in the loading direction. From the measured load and displacement data, force-displacement relations at contacts between the particles, and between the particles and mold wall were determined. In the simulation, the two-dimensional complex mold consisting of three stages (upper stage:3-mm wide and 1-mm deep, middle stage:2-mm wide and 1-mm deep, lower stage:1-mm wide and 1-mm deep) was charged with the copper powder consisting of spherical particles with size range of 50 to 200microns and was pressed under four press conditions. Forces at all contacts were calculated by using the determined force-displacement relations and each particle's position was traced by solving equations of motion for each particle. Pressure at each wall of the mold and density distribution in the powder compact were calculated as results of the simulation. It was found that the increase in the pressure at each wall corresponds to the increase in the density of the powder near the wall.
Dynamic Behavior of an Intruder in a Granular Couette Flow
Authors: Liu Jian , Rosato Anthony D. 
Published: April 2011

ABSTRACTThis paper reports on three-dimensional, steady discrete element simulations of a single large spherical intruder in a gravity-free granular Couette flow of uniform particles with diameterd.The non-equilibrium nature of the flow is characterized by the depth profile of granular temperature, which decreases inwards toward the center. An intruder of size φ =D/dmigrates away from the walls at a rate that increases with φ and wall velocityU.Computations indicated that the intruder's motion is induced by the high pressure near the wall.
Energy Absorption and Recovery in Tapered Granular Chains: Small Chains and Low Tapering
Authors: Pfannes Jan , Sen Surajit , Chakravarti Soumya , Surve Farhat I. 
Published: April 2011

AbstractShock absorption traditionally exploits visco-elastic devices, fluid viscous dampers and friction dampers, or “soft” materials. Recent work on impulse propagation in granular assemblies suggests that it may be possible to absorb shock waves using a different variety of shock absorbers and thus unlock the possibility of building structures that are significantly more shock absorbent than is currently possible, an issue of relevance to concerns of security. These new shock absorbers are composed of granular materials and exploit the nonlinear energy propagation properties in assemblies of granular materials. They have the potential to partially recover the energy of the absorbed shock waves for useful purposes, a property that might allow one to design devices to convert the incident energy to other useful forms. The basic physics of the “tapered chain shock absorber” is briefly discussed in this work.
Using Interactive Multimedia Tools to Teach Materials Characterization Techniques in the Undergraduate Curriculum
Authors: Prüβner Karin , Pingel Klaus , Becker Jens , Dressel Horst-Peter , Undynko Alexander , Reiner Christof , Schlosser Marc , Christ Hans-Jürgen 
Published: April 2011

ABSTRACTThe paper describes an ongoing project at the University of Siegen to develop multimedia teaching/learning software for materials characterization techniques in an effort to improve the quality of teaching and learning and to increase interest in scientific and engineering subjects in younger students. We have developed a modular web-based teaching platform that uses multimedia tools to provide access to and information about state-of-the-art analytical techniques, visualize complex physical concepts, and use interactive and animated modules to improve student learning.
An Instructional Two-Dimensional Diffraction Laboratory Using Patterns Created with Electron-Beam Lithography
Authors: Inglefield Colin , Anthon Royce 
Published: April 2011

ABSTRACTAn instructional laboratory in two-dimensional diffraction is discussed. The experiment is appropriate for undergraduate students in materials science, solid-state physics (as was the case with our group), modern physics, or optics. The experiment is performed using visible light from a laser incident on a 2D lattice of gold dots deposited with electron beam lithography on a glass substrate. The pattern is microscopic with a lattice constant on the same order of magnitude as the wavelength of light used. Students observe the diffraction pattern, and then quantitatively determine the positions of maxima. These data are used by the students to reconstruct the (real space) microscopic lattice. The students can simulate the experiment with software that computes reciprocal lattice and diffraction patterns for an arbitrary 2D lattice.
Non-Destructive Techniques for the Characterization of Structural Materials: Materials Science & Engineering Curriculum for the Education of an Innovative Model
Authors: Moropoulou Antonia , Aggelakopoulou Eleni , Avdelidis Nicolas P. , Koui Maria 
Published: April 2011

ABSTRACTIn this paper, the example of the Materials Science and Engineering (MSE) Curriculum that exists as a scientific direction in the undergraduate programme of the Chemical Engineering School, in the National Technical University of Athens (NTUA), in Greece, is presented. The course content includes several tools, such as theoretical lessons, laboratory modules - nondestructive testing (NDT) and instrumental techniques - semi industrial scale devices, fieldworks and a dissertation thesis. The presented curriculum can be regarded as an innovative educational model for chemical engineering students that choose to become involved in the field of MSE.
Alignment and Deposition of Single Wall Carbon Nanotubes under the Influence of an Electric Field
Authors: Jaynes Paul , Tiano Thomas , Roylance Margaret , Carey Charles , McElrath Kenneth 
Published: April 2011

ABSTRACTSingle wall carbon nanotubes have aroused a great deal of interest because of their unique combination of electrical, physical and mechanical properties. However, the widespread use of SWNTs in composites and electronic devices is limited because of the difficulty of dispersing and processing these materials. This paper describes a method for depositing and aligning SWNTs from a dispersed solution onto a substrate under the influence of an electric field. Results indicate that SWNTs can be aligned in bulk in the direction of electric field lines, and that individual SWNT ropes may be deposited between two electrodes. The extent and type of deposition depends upon the electrode geometry and processing time. Electrical alignment of SWNTs is an enabling technology allowing manipulation of nanomaterials using standard processing. It could eventually lead to a wide range of products, such as nanocomposites with aligned fillers and nanoelectronic devices.
Wireless and RF Module Packaging using Low Loss Ceramic and Low Loss Organic Materials
Authors: Logothetis James J. , Amey Daniel I. , Mobley Timothy P. 
Published: April 2011

ABSTRACTThis presentation describes the basics of Multi-Mix® and Green Tape™ Low Temperature Cofired Ceramic (LTCC) technologies. The design and performance of a 28 GHz mixer package using a GaAs MMIC and the 943 Green Tape™ LTCC system with embedded capacitance technology is described including the tradeoffs, advantages and compatibility of Multi-Mix® and Green Tape™ technologies. A design approach combining the technologies offers the designer new options to meet the ever-increasing demands of high frequency packaging.
Micr owave Dielectric Properties of (1-x)CaTiO3-xNd(Mg1/2Ti1/2)O3 Ceramics System
Authors: Huang Cheng-Liang , Chen Yuan-Bin , Lo Ching-Wen 
Published: April 2011

ABSTRACTThe microwave dielectric properties of (1-x)CaTiO3-xNd(Mg1/2Ti1/2)O3 (0.1≤x≤1.0) have been investigated. The system forms a solid solution throughout the entire compositional range. The dielectric constant decreases from 152 to 27 as x varies from 0.1 to 1.0. In the (1-x)CaTiO3-xNd(Mg1/2Ti1/2)O3 system, the microwave dielectric properties can be effectively controlled by varying the x value. A maximum quality factor Qxf=43000GHz (where f is the resonant frequency) was achieved for samples with x=0.9, although the dielectric properties varied with sintering temperature. The Qxf value of (1-x)CaTiO3-xNd(Mg1/2Ti1/2)O3 almost increased up to 1500°C, after which it decreased. At 1400°C, 0.1CaTiO3-0.9Nd(Mg1/2Ti1/2)O3 ceramics gives a dielectric constant εr of 42, a Qxf value of 35000 (GHz) and a τf value of -10 (ppm/°C).