| Electron Microscopy of Tungsten Disulphide Inorganic Nanomaterials |
Sep-2009 |
13 pages |
| Authors:
Stacey Kerwien; Tapan Chatterjee; Elias Jelis; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ
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 | Transmission and scanning electron microscopy studies of tungsten disulphide nanomaterials revealed nanotubes and onion-like structures. An electron diffraction pattern confirmed the lattice image of this nanotube. The tungsten disulphide nanomaterials exhibiting this kind of nanotubes will be useful as solid lubricant materials. |
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| An Analysis of Multiple Configurations of Next-Generation Cathodes in a Low Power Hall Thruster |
Mar-2009 |
151 pages |
| Authors:
John E Rotter; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The research presented here is an effort to integrate an existing hollow cathode design with a low power production Hall thruster in multiple geometries. Both externally- and internally-mounted cathodes were fabricated and operated in conjunction with a Busek BHT-1500 Hall thruster. Three insert materials were evaluated; Cerium Hexaboride (CeB6), Lanthanum Hexaboride (LaB6), and impregnated tungsten. The thruster was operated at a single operating condition for all testing. The operating specifications ... |
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| Shock Processing and High Strain Rate Properties of Bulk Metallic Glasses and Their Composites |
26-Sep-2008 |
10 pages |
| Authors:
Naresh Thadhani; Morgana Martin; GEORGIA INST OF TECH ATLANTA SCHOOL OF MATERIALS SCIENCE AND ENGINEERING
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| The dynamic mechanical behavior of a Zr-based bulk metallic glass and its composite with tungsten has been investigated to determine the deformation response over a range of stress states, strain rates, and temperatures. The equation of state (EOS) of the monolithic glass has also bee investigated to determine its phase stability. Anvil-on-rod impact experiments performed on the BMG (with and without steel sleeve) reveal the deformation, fracture, and elastic-plastic wave ... |
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| Modulation of Coulomb Blockade Behavior of Room Temperature Operational Single Electron Transistors by Tunnel Junction |
Aug-2008 |
5 pages |
| Authors:
P S Karre; Aditya Kapoor; Govind Mallick ;Shashi P Karna; Paul L Bergstrom; MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| The effect of tunneling oxide thickness on the Coulomb blockade behavior of a room temperature operating multi dot Single Electron Transistors (SET) was investigated. Our room temperature operational SETs, fabricated from focused ion beam deposited tungsten nano-islands, clearly show the modulation of Coulomb Blockade voltage with the change in the tunnel oxide thickness. The Coulomb blockade voltage of the device was increased from 2.0 V to 5.0 V by the ... |
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| Heterogeneous Deformation and Spall of an Extruded Tungsten Alloy: Plate Impact Experiments and Crystal Plasticity Modeling |
01-Apr-2008 |
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| Authors:
T J Vogler; J D Clayton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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 | The role of microstructure in the dynamic deformation and fracture of a dual phase, polycrystalline tungsten alloy under highrate impact loading is investigated via experiments and modeling. The material studied consists of pure tungsten crystals embedded in a ductile binder alloy comprised of tungsten, nickel, and iron. The tungsten crystals are elongated in a preferred direction of extrusion during processing. Plate impact tests were conducted on samples oriented either perpendicular ... |
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| Development and Optimization of a Positron Annihilation Lifetime Spectrometer to Measure Nanoscale Defects in Solids and Borane Cage Molecules in Aqueous Nitrate Solutions |
01-Mar-2008 |
103 pages |
| Authors:
Matthew A Ross; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| A Positron Annihilation Lifetime Spectroscopy (PALS) system was developed and tested. PALS has the capability to characterize negatively charged defects and voids in materials such as explosives. The timing resolution of the optimized system is 197 +or- 14 ps as measured with a known (60)Co source. A single-crystal tungsten sample was used to confirm the system calibration resulting in a lifetime of 101 +or- 2 ps (as compared to 105 ... |
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| Neurobehavioral Effects of Sodium Tungstate Exposure on Rats and Their Progeny |
30 JUN 2007 |
25 pages |
| Authors:
S. M. Mclnturf; M. Y. Bekkedal; A. Olabisi; D. Arfsten; E. Wilfong; R. Casavant; W. Jederberg; P. G. Gunasekar; G. CHAPMAN; NAVAL HEALTH RESEARCH CENTER (DET) WRIGHT-PATTERSON AFB OH ENVIRONMENTAL HEALTH EFFECTS LAB
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| In the mid 1990's, the use of tungsten as a replacement for lead and depleted uranium began for the manufacture of small arms munitions and armor penetrator munitions, respectively. Recent reports have demonstrated that tungsten can solubilize in soil and is present in some US drinking water supplies, however, little research has been conducted to determine the human health consequences of exposure. The purpose of this study was to use ... |
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| Nanocrystalline and Ultra-Fine Grained Tungsten for Kinetic Energy Penetrator and Warhead Liner Applications |
JUN 2007 |
14 pages |
| Authors:
Kyu Cho; Laszlo Kecskes; Robert Dowding; Brian Schuster; Qiuming Wei; Ruslan Z. Valiev; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| For the first time, we have demonstrated adiabatic shear localization in pure, ultra-fine grain (UFG) and nanocrystalline (NC) tungsten (W). Fabricated by severe plastic deformation (SPD), microstructural and mechanical property analyses of the W samples show that the combination of fine grain size, stored strain energy, ultra-high strength, little or no work hardening capacity leads to a unique flow softening behavior. It is further hypothesized that, while maintaining material ductility, ... |
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| Field Emission and Particle Sensing Devices Based on Arrayed Carbon Nanotubes and Related Nanostructures for Defense Applications |
01-Apr-2007 |
23 pages |
| Authors:
Li-Chyong Chen; Kuei-Hsien Chen; NATIONAL TAIWAN UNIV TAIPEI CENTER FOR CONDENSED MATTER SCIENCES
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| This project covered efforts to develop and test the field-emission and particle sensing devices (FED and PSD) using carbon nanotubes (CNTs), and SiC capped Si nanotips (SiNTs) arrays. Additional studies focused on tungsten nanotips. The report covers successes on all efforts, including structural characterization and tip performance. |
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| Multiscale Modeling of Point and Line Defects in Cubic Lattices |
01-Jan-2007 |
30 pages |
| Authors:
J D Clayton; P W Chung; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| A multilength scale method based on asymptotic expansion homogenization (AEH) is developed to compute minimum energy configurations of ensembles of atoms at the fine length scale and the corresponding mechanical response of the material at the coarse length scale. This multiscale theory explicitly captures heterogeneity in microscopic atomic motion in crystalline materials, attributed, for example, to the presence of various point and line lattice defects. The formulation accounts for large ... |
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| A Multiscale Modeling Method for Deformations on Atomic Lattice Defects and Application to Plasticity |
NOV 2006 |
27 pages |
| Authors:
Peter W. Chung; John D. Clayton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Computing the displacements of atoms undergoing deformation in a perfect lattice requires the use of the so-called Cauchy-Born approximation. Near defects such as at vacancies or dislocations, this approximation does not hold and a computationally costly energy minimization over a large number of atoms is unavoidable. Presented is a self-consistent multiscale methodology enabling an approximation to the displacements near defects without requiring full energy minimization over successive load increments. It ... |
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| Effect of Nanoparticles on Complement System in Cell Culture Model |
15 SEP 2006 |
21 pages |
| Authors:
Dariusz T. Sladowski; MEDICAL UNIV OF WARSAW (POLAND)
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| The research focused on complement activation by nanoparticles which have been already tested in cell culture by AFRL/HEPB Identification of complement activation pathways was carried out by evaluation of the concentration of pathway specific complement split products generated during human plasma exposure to nanoparticles, Measurements were performed using assay kits supplied by QUIDEL Corporation San Diego California, Different sizes of nanoparticles such as silver (Ag; 151,000 nm) molybdenum (MoO3; 30 ... |
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| The Effect of Slug Material on the Behavior of Small-Caliber Ammunition |
SEP 2006 |
22 pages |
| Authors:
Joseph South; Aristedes Yiournas; Michael Minnicino; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The drive to produce environmentally friendly "green" ammunition has shifted focus to alternate materials for the lead cores in small-arms ammunition. Candidate materials such as tungsten-nylon and tungsten-tin have been evaluated as possible replacements. This research is aimed at evaluating the response of the candidate materials as well as the current M855 "lead" round. Experiments were conducted on sheathed and unsheathed slug samples to determine their compressive response. It was ... |
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| The Influence of Armor Material Parameters on the Penetration by Long-Rod Projectiles |
SEP 2006 |
12 pages |
| Authors:
William P. Walter; Cyril L. Williams; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The Alekseevski-Tate equations have long been used to predict the penetration, penetration velocity, rod velocity, and rod erosion of long-rod projectiles or kinetic energy penetrators (1). These nonlinear equations were originally solved numerically, then by the exact analytical solution of Walters and Segletes (2, 3). However, due to the nonlinear nature of the equations, the penetration was obtained implicitly as a function of time, so that an explicit functional dependence ... |
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| Analysis of the Electrospray Plume from the EMI-Im Propellant Externally Wetted on a Tungsten Needle |
JUL 2006 |
9 pages |
| Authors:
Yu-Hui Chiu; Geraldine Gaeta; Thomas R. Heine; Rainer A. Dressler; Dale J. Levandier; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| The room temperature ionic liquid propellant, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-Im) is being tested for the NASA DRS-ST7 mission. A capillary thruster configuration is planned for ST7, and time-of-flight experiments have shown that the spray of EMI-Im produces a mixture of primarily droplets and low levels of ions, resulting in a low specific impulse. Recently, pure ion emission was achieved for EMI-Im in a wetted needle thruster, suggesting that this propellant, which ... |
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| NanoBench: An Individually Addressable Nanotube Array |
25 MAR 2006 |
43 pages |
| Authors:
Nalin Kumar; UHV TECHNOLOGIES INC FORT WORTH TX
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| There is an urgent need to determine the fundamental functions carried out by molecular machines inside biological cells at nanometer scale; however, the current technologies such as fluorescence are limited to a 100nm resolution. Atomic force microscopy (AFM), even with its nanometer resolution, has not been used for monitoring of internal signals because of lack of nanoscale probe arrays with individual addressability. Electron microscopy (EM), the other sub-nanometer resolution analytical ... |
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| Moisture Effects on Copper Thin Film Adhesion |
NOV 2005 |
5 pages |
| Authors:
Patrick J. Waters; Alex A. Volinsky; UNIVERSITY OF SOUTH FLORIDA TAMPA DEPT OF MECHANICAL ENGINEERING
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| The effects of moisture on copper thin film adhesion have been investigated using a modified version of the superlayer indentation test. Copper films up to 100 nm thick were sputter deposited on thermally oxidized silicon wafers. A 1 um tungsten superlayer with I GPa compressive residual stress was sputter deposited on top of Cu films, providing extra energy for interfacial debonding upon indentation. The samples were first indented to a ... |
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| Development of Advanced Oxide Dispersion Strengthened Tungsten Heavy Alloy for Penetrator Application |
30 SEP 2005 |
47 pages |
| Authors:
Soon H. Hong; Ho J. Ryu; Seung I. Cha; Hee Y. Kim; Kyung T. Kim; Kyong H. Lee; Chan B. Mo; KOREA ADVANCED INST OF SCIENCE AND TECHNOLOGY DAEJEON (KOREA)
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| The effects of fabrication process parameters, including conditions for powder preparation, sintering, cyclic heat-treatment, swaging, and annealing processes, on microstructures and static/dynamic mechanical properties of ODS tungsten heavy alloys were investigated. The composition of ODS tungsten heavy alloys was designed as 94W-4.56Ni-1.14Co-0.3Y2O3 which show the highest strength at similar microstructural parameters based on the analysis of microstructures and mechanical properties. The two-stage sintered ODS tungsten heavy alloy showed finer tungsten ... |
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| Generation and Study of Microwave Plasma Jets |
28 SEP 2005 |
19 pages |
| Authors:
Kuo; POLYTECHNIC UNIV BROOKLYN NY
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| The present report summarizes the work, under the support of the AFOSR Grant AFOSR-FA9550-O4-l-0352, starting at May 1, 2004. This research program is primarily aiming at developing plasma torches as igniters of a scramjet engine. For the hydrocarbon-fueled scramjet in a typical startup scenario, cold liquid JP-7 is injected into a Mach-2 air crossflow (having a static temperature of - 500 K); under these conditions, the fuel-air mixture will not ... |
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| Bending of Threaded and Unthreaded Tungsten Rods Under Oblique Impact |
28 SEP 2005 |
53 pages |
| Authors:
Martin N. Raftenberg; Todd W. Bjerke; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| We employed ballistic experiments and finite element (FE) analysis to explore the extent to which. and the mechanism by which, the threading on a tungsten heavy alloy rod increases its susceptibility to break up under conditions of oblique impact. In the laboratory. small-scale rods with and without threads were launched into thin rolled homogeneous armor plates at 1300 m/s and 60 degrees' obliquity. Fracture near the nose of the rod ... |
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| Spherical Indentation in Elastoplastic Materials: Modeling and Simulation |
MAY 2005 |
30 pages |
| Authors:
John D. Clayton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| An implicit axisymmetric finite element model is implemented to study the response of an elastoplastic substrate in contact with a rigid spherical indenter. A finite strain, rate-independent, isotropic elastic-plastic constitutive formulation is invoked for the behavior of the substrate. Relative influences on the load displacement response of elastic stiffness constants and plastic properties of the substrate are investigated via a series of simulations. With increasing depth of indentation, the flow ... |
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| Use of Self-Propagating High-Temperature Synthesis Reactions in Refractory Alloy Fabrication |
APR 2005 |
25 pages |
| Authors:
Laszlo J. Kecskes; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The titanium carbide (TiC) self-propagating high-temperature synthesis (SHS) reaction was used in a hot-explosive-consolidation process to fabricate tungsten and molybdenum-based alloy billets. In this method, a Ti+C mixture is reacted to provide a source of heat for the refractory precursor powders. As the TiC reaction proceeds, the exterior of the alloy sample heats up rapidly, near or above 2000 deg C, while its interior lags behind, heating up more gradually ... |
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| Task-Specific Optimization of Mammographic Systems |
MAR 2005 |
51 pages |
| Authors:
Robert Saunders; DUKE UNIV DURHAM NC
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| During this past year, our research has focused on four objectives. The first objective was to develop a simulation model for the radiographic appearance of breast masses and calcifications. This model was verified by a human observer performance experiment. The next objective explored the physical properties of a digital mammographic system, including resolution, noise, efficiency, and lag. The system was characterized for new beam qualities that used a tungsten anode, ... |
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| The Growth and Characterization of Metastable Free Radical Nanoclusters |
JUN 2004 |
7 pages |
| Authors:
Roger E. Miller; NORTH CAROLINA UNIV AT CHAPEL HILL DEPTOF CHEMISTRY
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| In the first three years of this grant we have made considerable progress towards the goals stated in the original proposal. To date we have made clean sources for propargyl radical, CH3, F, Cl, Br and I. A total of 11 papers have been published during this grant period. |
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| Vacuum Breakdown of Sub-Micrometer Gap with Pointed Electrode |
07 APR 2004 |
2 pages |
| Authors:
Y. Hirata; K. Ozaki; K. Fukatani; T. Takenaka; U. Ikeda; OSAKA UNIV (JAPAN) GRADUATE SCHOOL OF ENGINEERING
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| Vacuum breakdown of very small gap in the range of 30nm to 2f m, between a pointed cathode of thin tungsten wire and a plane anode of stainless steel, was experimentally investigated. The experimental setup, which consists of both electrodes and precise positioning mechanisms actuated by piezoelectric devices, was installed in scanning electron microscope (SEM). Breakdown voltage decreases with decrease of gap spacing and/or radius of curvature at the tip ... |
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| Recombining Plasma Expanding in Low-Pressure Region |
07 APR 2004 |
1 pages |
| Authors:
R. P. Dahiya; INDIAN INST OF TECH NEW DELHI
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| High density thermal plasma expanding in low-pressure region is of immense scientific interest and has numerous applications. The monomer seeded plasma is utilized for plasma processing of surfaces, i.e. deposition, surface etching, nitriding and for many more applications depending on the seeding materials. Conditions prevailing in the Tokomak edge plasma can also be simulated using the low temperature, high flux obtained with cascaded arc thermal plasma source. Various species of ... |
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| Fabrication of Dense, Near Net-Shaped W/ZrC Composites by the PRIMA-DCP Process |
FEB 2004 |
42 pages |
| Authors:
Ken H. Sandhage; GEORGIA INST OF TECH ATLANTA SCHOOL OFMATERIALS SCIENCE AND ENGINEERING
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| The fundamental conversion mechanism for the following net liquid/ solid displacement reaction has been examined: (Zr) + WC(s) =ZrC(s)+W(s) (1) where (Zr) refers to zirconium dissolved within a Zr-Cu melt. Such mechanistic knowledge is needed in order to be able to predict the time required, under various processing conditions, for full conversion of porous WC performs into dense ZrC/W composites (e.g., for rocket nozzle applications) by the DCP method. For ... |
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| Near Net-Shape, Ultra-High Melting, Recession-Resistant ZrC/W-Based Rocket Nozzle Liners via the Displacive Compensation of Porosity (DCP) Method (POSTPRINT) |
2004 |
12 pages |
| Authors:
M. B. Dickerson; P .J. Wurm; J. R. Schorr; W. P. Hoffman; P. G. Wapner; K. H. Sandhage; GEORGIA INST OF TECH ATLANTA SCHOOL OF MATERIALS SCIENCE AND ENGINEERING
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| Dense, near net-shaped ZrC/W-based composites have been fabricated at modest temperatures and at ambient pressure by a reactive infiltration process known as the Displacive Compensation of Porosity (DCP) method. Porous WC preforms with hourglass shapes (for rocket nozzle liners) were produced by gel casting, whereas simple bar-shaped preforms were produced by uniaxial pressing. The porous preforms were exposed to molten Zr2Cu at 1200-1300 deg C and ambient pressure. The Zr2Cu ... |
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| New Perspectives for the Production and Accumulation of (178m2)Hf Isomers |
30 SEP 2003 |
21 pages |
| Authors:
Ioan-Iovitz Popescu; ROMANIAN CENTER FOR INDUCED GAMMA EMISSION BUCHAREST (ROMANIA)
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| This report results from a contract tasking Induced Gamma Emission Foundation as follows: The contractor will investigate the production and accumulation of the nuclear isomer 178m2 Hafnium by spallation of Tungsten targets with high-energy protons. Targets made of the isotope 186 Tungsten will be designed using the LAHET computer code, and fabricated for experimental verification. The Hafnium yield will be assayed and compared to LAHET calculations. |
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| Plasma of Free Burning Electric Arc between Composition Electrodes in Air |
20 JUL 2003 |
2 pages |
| Authors:
A. N. Veklich; I. L. Babich; V. Ye. Osidach; L. A. Kryachko; R. V. Minakova; TARAS SHEVCHENKO UNIV OF KYIV (UKRAINE)
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| This paper deals with spectroscopy investigations of plasma of free burning electric arcs in air between electrodes from composition materials on the base of cooper (Cu, Cu- W, Cu-Mo, Cu-Mo- LaB6) and silver (Ag, Ag - CdO, Ag - Ni). |
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| Composite Materials in Aircraft Mishaps Involving Fire: A Literature Review |
JUN 2003 |
107 pages |
| Authors:
Mark T. Wright; Ariam C. Luers; Robert L. Darwin; Joseph L. Scheffey; Howard L. Bowman; NAVAL AIR WARFARE CENTER WEAPONS DIV CHINA LAKE CA
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| When Navy aircraft are involved in crash incidents, firefighters must be aware of hazards presented by airframe composite-material construction. Composite matrices may be combustible, contributing to the aircraft fuel load and burning hazard. Additionally, fibers released from burning composites may present a respiration hazard to firefighters. Current Navy and military doctrine recognize these hazards; cautionary guidance is provided for composite materials reinforced with carbon/graphite fibers and boron/tungsten fibers. The Naval ... |
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| Versatile Nanodeposition of Dielectrics and Metals by Non-Contact Direct-Write Technology |
APR 2003 |
7 pages |
| Authors:
H. D. Wanzenboeck; H. Langfischer; S. Harasek; B. Basnar; H. Hutter; VIENNA UNIV OF TECHNOLOGY (AUSTRIA) INSTITUTE FOR SOLID STATE ELECTRONICS
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| Direct-write techniques allow processing in the nanometer range and have become powerful methods for rapid prototyping of microelectronic circuits and micro-electro-mechanical systems (MEMS). Chemical reactions are initiated by a focused beam leading to deposition of solid material on literally any surface. We have used this method to deposit metals such as tungsten and dielectrics such as silicon oxide using a focused ion beam (FIB) with 10 to 50 kV acceleration ... |
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| Electrodeposition of Ni Catalyst on Tungsten Substrates and Its Effect on the Formation of Carbon Nano- and Micro-coils |
2003 |
6 pages |
| Authors:
Erik Einarsson; Jun Jiao; Josie Prado; George M. Coia; PORTLAND STATE UNIV OR DEPT OF PHYSICS
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| Carbon micro-coils and nano-coils were produced in high yield from nickel catalyst particles electrochemically deposited onto tungsten substrates. Various electrochemical deposition techniques were used to produce the nickel catalyst particles. These particles catalyzed the chemical vapor deposition (CVD) of acetylene at 800 deg. C, resulting in growth of carbon micro- and nano-coils. Linear-sweep (cyclic) voltammetry produced catalyst particles which resulted in single-filament coils intermixed with thin nanotubes over most of ... |
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| Near Net-Shape Ultra-High Melting Recession-Resistant Rocket Nozzles II: Low Cost Carbon-Carbon Technology for Use in Ultra-High Temperature Oxidative Environments |
2003 |
20 pages |
| Authors:
W. P. Hoffman; P. G. Wapner; P. J. Wurm; J. R. Schorr; K. H. Sandage; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| Carbon-carbon composites are ideal materials for high temperature structural uses, such as in rocket propulsion components, hypersonic vehicles, and aircraft brakes. In spite of their excellent properties, the use of carbon- carbon composites has been limited because of their high cost and rapid oxidation at elevated temperatures. Two novel approaches to solving these problems are described and these approaches are employed along with a ZrC/W- based nozzle insert to fabricate ... |
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| Bulk Nanostructured Refractory Metals with Enhanced Mechanical Properties Produced by Equal Channel Angular Pressing |
11 DEC 2002 |
6 pages |
| Authors:
R. Z. Valiev; I. V. Alexandrov; UFA STATE AVIATION TECHNICAL UNIV (RUSSIA) INST OF PHYSICS OF ADVANCED MATERIALS
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| The air of the present project is to obtain a set of bulk billets 100 mm long with UFG structure made of refractory metals such as tungsten and tantalum. The previous positive experience of refining the tungsten's structure using equal channel angular pressing (ECAP) was taken into account. For the production of bulk billets with UFG structure having a more long-lengthed size than those obtained in earlier works, it has ... |
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| Surface Heating of Molybdenum, Tantalum, and Tungsten Rods by Pulsed Currents |
NOV 2002 |
40 pages |
| Authors:
Charles R. Hummer; John D. Powell; Paul R. Berning; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Measurements of the surface voltage and surface temperature are made for small molybdenum, tantalum, and tungsten rods that have been subjected to pulsed electrical heating. The heating time is from 100 to 200 microseconds. The experimental results are then compared to results obtained from calculations undertaken with a numerical model that accounts for diffusion of current and ohmic heating within the sample. Good agreement between theory and experiment is obtained ... |
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| Penetration of a Highly Oblique Steel Plate by a Thin Disk |
SEP 2002 |
28 pages |
| Authors:
Nathaniel Bruchey; Kent Kimsey; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Segmented rod penetrator concepts created interest in the ballistic performance of high-density, low length-to-diameter (LID) ratio penetrators, but there was a lack of data showing the performance of such thin disks vs. high- obliquity targets. An experimental and computational study was conducted to examine the basic case of a single tungsten heavy alloy disk with an LID of 1/8 impacting a high-obliquity (65 degrees) rolled homogeneous armor steel plate at ... |
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| High Resolution Core-Level Photoemission Spectroscopy of Semiconductor- Oxide and Metal-Metal Interfaces |
MAY 2002 |
26 pages |
| Authors:
John E. Rowe; Theodore E. Madey; RUTGERS - THE STATE UNIV PISCATAWAY NJOFFICE OF RESEARCH AND SPONSORED PROGRAMS
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| The focus of this project is the characterization of two types of interfaces of technological importance: SiO2/Si interfaces relevant to ultra thin gate oxides used for next-generation semiconductor electronics, and bimetallic interfaces (ultra thin films of metals on other metals) that have potential catalytic applications. The main tool is high resolution soft x-ray photoemission spectroscopy (SXPS) using synchrotron radiation at the National Synchrotron Light Source (NSLS). Device-grade films of silicon ... |
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| Stabilization and Confinement of Hot, Dense, High-Beta Plasma |
14 FEB 2002 |
409 pages |
| Authors:
Bruno S. Bauer; Victor L. Kantsyrev; Nathalie Le Galloudec; Volodymyr Makhin; Roberto C. Mancini; NEVADA UNIV RENO
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| A calibrated, high-repetition rate 2-terawatt z-pinch (Zebra) was developed, and new z-pinch physics was investigated. Investigation of axial- shear-flow z-pinch stabilization was initiated, with experiments, computer modeling, and theory. An experiment on single wires driven by current prepulses similar to, and faster than, those at Z (SNL) found that faster rising pulses are much more effective at exploding single tungsten wires than Z-like pulses. Experiments on x-pinches driven at 900 ... |
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| Nanostructures and Enhanced Properties in Tungsten and its Alloys Processed by Equal Channel Angular Pressing |
10 JAN 2002 |
5 pages |
| Authors:
R. Z. Valiev; I. V. Alexandrov; UFA STATE AVIATION TECHNICAL UNIV (RUSSIA) INST OF PHYSICS OF ADVANCED MATERIALS
|
| In this connection, in the frame of the third period of the present project there have been conducted experimental investigations, aimed at equal channel angular pressing (ECAP) optimization of the investigated W and the 90W- 8Ni-2Fe alloy. The problem of this task consists in enhancing workability of these hard-to-deform materials and achieving large strains, The influence of the accumulated strain degree the thickness of protection casing, the rate and strain ... |
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| Nanostructures and Enhanced Propertiesin Tungsten and its Alloys Processed by Equal Channel Angular Pressing |
10 OCT 2001 |
5 pages |
| Authors:
R. Z. Valiev; I. V. Alexandrov; UFA STATE AVIATION TECHNICAL UNIV (RUSSIA) INST OF PHYSICS OF ADVANCED MATERIALS
|
| The present report presents the results of an experimental investigation and numerical simulation of the process of equal-channel angular pressing with a backpressure equal to 2.4 sigma(sub s) which have allowed to increase the accumulated strain rate up to e=7, what allows to obtain ultrafine- grained structure with a grain size less than 0.5 micrometers. Note should be made that in that case the punch loading was close to its ... |
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| On the Aerodynamic Heating of a KE Pentrator - Conductive Material Heating and Thermal Gradients Prior to Transient Impact Loading |
SEP 2001 |
30 pages |
| Authors:
Todd W. Bjerke; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The temperature increase in the main body portion of a kinetic energy penetrator flying at sea level with a speed of 1,500 m/s was calculated using an analytical conduction analysis with a convective boundary condition. The penetrator was modeled as a smooth cylinder of uniform diameter and material properties. The results from a previously published computational fluid dynamics simulation were used to provide the convective heat transfer coefficient and the ... |
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| Training Munitions Health Risk Assessment No. 39-EJ-1485-00 Residential Exposure from Inhalation of Air Emissions from the M855 5.56-MM Tungsten Ball Cartridge |
04 JUN 2001 |
102 pages |
| Authors:
Joleen Mobley; Stafford Coakley; ARMY CENTER FOR HEALTH PROMOTION AND PREVENTIVE MEDICINE ABERDEEN PROVING GROUND MD ENVIRONMENTAL HEALTH ENGINE
|
| This assessment evaluated the potential for human health effects to offsite residents breathing air emissions following use of the 5.56mm Tungsten Ball Cartridge. This document present the evaluation of the potential for adverse human health effects to the offsite residents breathing air emissions following the use of military firing ranges during training exercises. Study results showed no potential for health risks to the hypothetical resident from inhalation of air emissions ... |
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| Normal-to-Plane Magnetoresistance of Single Crystalline Refractory Metal Nanostructures |
JUN 2001 |
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| Authors:
G. M. Mikhailov; I. V. Malikov; A. V. Chernykh; L. A. Fomin; P. Joyez; RUSSIAN ACADEMY OF SCIENCES CHERNOGOLOVKA (RUSSIA) INST OF MICROELECTRONICS TECHNOLOGY
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| We have performed normal-to-plane magneto transport measurements in single crystalline (100) W and Mo nanostructures down to 1.5 K. Fabricated nanostructures possess large mean free path due to their bulk crystalline perfection and low surface roughness. Under these conditions electrons scatter only on the boundaries of nanostructures and may travel long distance without scattering. We found that in this regime the normal-to-plane magnetoresistance of planar metallic nanostructures exhibit specific for ... |
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| High Strength Soft Magnetic Composites |
APR 2001 |
6 pages |
| Authors:
Ronghai Yu; Michelle M. Corte-Real; Adrian Gorea; Libo Ren; Azar Parvizi-Majidi; DELAWARE UNIV NEWARK
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| There has been an increasing demand for high temperature soft magnetic materials with mechanical properties better than those of existing commercial materials such as FeCo alloys. We have designed new magnetic composites by reinforcing FeCo alloys with high strength tungsten fibers. The composite materials were fabricated by electrodeposition. In general, the as deposited composites have a relatively high coercivity H(sub c) and low magnetic permeability Micro, because of induced strain ... |
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| Effect of Metal Back Contacts on Tetrahedral Amorphous Carbon Films Grown Using the Cathodic Arc Process |
APR 2001 |
6 pages |
| Authors:
B. S. Satyanarayana; H. Takahashi; T. Narusawa; A. Hiraki; KOCHI UNIV OF TECHNOLOGY (JAPAN) ACADEMIC AND INDUSTRIAL COLLABORATION CENTRE
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| Reported here is a study on the effect of different metal back contacts on the electrical and structural properties of the tetrahedral amorphous carbon (ta-C). The films were grown using a pulsed cathodic arc system. Ta-C films were deposited simultaneously on silicon substrate, precoated with the following metals, namely aluminium (Al), gold (Au), chromium(Cr), molybdenum (Mo), copper (Cu), tungsten (V) and titanium(T1). The electrical measurements and Raman response show that ... |
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| Synthesis of Vertically Aligned Carbon Nanofiber Films by RF Magnetron Sputtering |
APR 2001 |
4 pages |
| Authors:
K-Y. Lee; K. Fujimoto; S. Ohkura; S. Honda; M. Katayama; OSAKA UNIV (JAPAN)
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| The aligned carbon nanofibers were synthesized on Si substrates using RF magnetron sputtering with a hot filament. The hot filament was made of tungsten wire and its temperature was up to 2000 degrees C during the deposition. Nitrogen was used as the sputter gas at a relatively low pressure of 2xlO(exp-2) Torr. The sputtering deposition was carried out at a substrate temperature of 700 degrees C. The nanofibers were grown ... |
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| Atmospheric Pressure Plasma an Electron Cyclotron Resonance Plasma and Their Applications |
31 OCT 2000 |
65 pages |
| Authors:
Spencer Kuo; Daniel Bivolaru; POLYTECHNIC INST OF NEW YORK FARMINGDALE DEPT OF ELECTRICAL ENGINEERING
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| The installation of an array of plasma torches is made easy by introducing a cylindrically shaped plasma torch module, which has been designed and constructed by remodeling components from two commercially available spark plugs and adding a tungsten wire as the central electrode. Use of modules as building blocks of a large volume plasma source also makes it easy to maintain the plasma source. This plasma torch module has been ... |
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| Quiet, Clean, Multi-fueled, Multi-kilowatt Thermophotovoltaic Generator |
20 OCT 2000 |
18 pages |
| Authors:
Michael Seal; WESTERN WASHINGTON UNIV BELLINGHAM
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| A stand-alone generator that is capable of producing one kWatt was developed during the contract period. Power to weight ratio has been improved from 10 Watts/K to 50 Watts/K. Exhaust emissions are less than 1 PPM HC and 300 PPM CO. NOx emissions are still high but a Rhodium or Rubidium flash coating on the metal recuperator surface should get below the 15 PPM target. The ... |
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| Low-Coherence Interference Microscopy at High Numerical Apertures |
JUL 2000 |
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| Authors:
C. J. Sheppard; M. Roy; P. Svahn; SYDNEY UNIV (AUSTRALIA) SCHOOL OF PHYSICS
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| A white-light Linnik interference microscope using high numerical aperture optics has been constructed. The system uses a tungsten halogen source and Koehler illumination with separate control over field and aperture stops, so that experiments can be conducted with a range of different operating conditions. Infinity tube length objectives are used in the two arms. Images are recorded with a CCD camera. Different algorithms have been investigated for extraction of information ... |
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