| Processing for Highly Efficient AlGaN/GaN Emitters |
09-Sep-2009 |
14 pages |
| Authors:
Ilesanmi Adesida; ILLINOIS UNIV AT URBANA-CHAMAPAIGN
|
 | The fabrication of high-quality ohmic contacts on n- and p-type (Al,In)GaN is essential for improving the performance of optoelectronic devices, such as blue light emitting diodes, metal-semiconductor field effect transistors, HEMTs, and laser diodes. In particular, to realize solid-state UV emitters for chembioagent detection and general lighting, the formation of reliable ohmic contact systems for both n- and p-AlGaN with relatively high Al contents are indispensable. In conjunction with efforts ... |
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| Effect of Steam Environment on Creep Behavior of Nextel720/Alumina-Mullite Ceramic Matrix Composite at Elevated Temperature |
Mar-2009 |
426 pages |
| Authors:
Tolga Kutsal; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| The tensile creep behavior of an oxide-oxide ceramic matrix composite (CMC) was investigated at 1000 and 1100 deg C in laboratory air and steam. The oxide-oxide CMC studied in this research was Nextel(trademark)720/alumina-mullite (N720/AM). The composite consists of N720/fibers with 0 deg/90 deg fiber orientation and a porous alumina-mullite matrix. Tensile-strain behavior was investigated and tensile properties measured at 900, 1000 and 1100 deg C. The effect of loading rate ... |
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| Effects of Environment On Creep Behavior of Nextel720/Alumina-Mullite Ceramic Composite With 45 Deg. Fiber Orientation at 1200 Deg. C |
Mar-2009 |
501 pages |
| Authors:
Muzaffer Ozer; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The present effort will investigate the off-axis creep behavior of the Nexte720/Alumina-Mullite CMC, a material system which relies on a porous alumina/mullite matrix for damage tolerance as compared to the pure alumina matrix in earlier studies. This research evaluated the creep behavior of N720/AM with a +/- 45 degree fiber orientation at 1200 degrees C in: laboratory air, steam, and argon environments. Creep-rupture tests at the creep stress levels of: ... |
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| Ceramic Matrix Composite Characterization Under a Combustion and Loading Environment |
Mar-2009 |
120 pages |
| Authors:
Andrew R Nye; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| Lightweight materials that can withstand high temperatures and corrosive environments are constantly sought after in the aerospace industry, typically for Gas Turbine Engine (GTE) application. These materials need to retain their strength throughout the long service period they would see in the combustor and turbine components of a GTE. One material that is ideal for these types of applications is an oxide/oxide Ceramic Matrix Composite (CMC). The fatigue behavior of ... |
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| New Thermal Protection Concepts for the Next Generation Gas Turbines and Hypersonic Vehicles |
Dec-2008 |
7 pages |
| Authors:
David R Clarke; CALIFORNIA UNIV REGENTS SANTA BARBARA OFFICE OF RESEARCH
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| Thermal protection of gas turbine blades, combustors and some rocket nozzles is generally provided by thin superficial layer coatings of yttria-stabilized zirconia (YSZ). This material, deposited by either electron-beam physical vapor deposition or plasma-spraying, has exceptionally low thermal conductivity up to high temperatures but its resistance to radiative heat transport is not known in any detail. Although oxides with still lower thermal conductivity at high temperatures than YSZ have been ... |
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| Investigation into the Effect of Reagent Choice on the Dielectric Properties of the Ferroelectric Oxides Ba(MTa)0.05Ti0.9O3 (where M=Sc, Er, Ho or Y) |
01-Oct-2008 |
24 pages |
| Authors:
Virginia L Miller; Steven C Tidrow; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
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| This report investigates the effects of reagent choice on the physical properties of ferroelectric oxides of the composition Ba(MTa)0.05Ti0.9O3 (M=Sc, Er, Ho or V). These materials are of particular interest because they possess relatively low to medium dielectric constants and improved tunabilities. In this project, samples of Ba(MTa)0.05Ti0.9O3 (M=Sc, Er, Ho or Y) were prepared using two different synthetic methods. The first method consisted of heating a stoichiometric mixture of ... |
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| Historical Perspective and Contribution of U.S. Researchers Into the Field of Self-Propagating High-Temperature Synthesis (SHS)/Combustion Synthesis (CS): Personal Reflections |
01-Jul-2008 |
80 pages |
| Authors:
James W McCauley; Jan A Puszynski; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| This report presents an historical perspective and contributions of U.S. researchers into the field of Self-Propagating High-Temperature Synthesis (SHS)/Combustion Synthesis (CS) and personal reflections of the authors from about 1976 to the present for a special meeting in Chernogolovka, Russia - SHS-40 - celebrating 40 years of SHS research (International Conference on Historical Aspects of SHS in Different Countries, 22-27 October 2007, Chernogolovka, Russia). The review is presented in the ... |
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| Ultra-Fast Image Sensor Using Ge on Insulator MIS/Schottky Detectors |
28 MAY 2008 |
26 pages |
| Authors:
Chee-Wee Liu; NATIONAL TAIWAN UNIV TAIPEI DEPT OF ELECTRICAL ENGINEERING
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| The Ge-on-insulator has been fabricated by wafer bonding and smart-cut. The MIS structure leads to simple fabrication process as compared to the conventional PIN structure. Due to the small band gap of Ge, 1.3 microns and 1.55 microns infrared beside 850 nm can be detected. The low parasitics of GOI structure also increase the detection speed. The large work function metal (Pt) is used for the gate electrode to reduce ... |
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| The Study and Development of Metal Oxide Reactive Adsorbents for the Destruction of Toxic Organic Compounds |
15 APR 2008 |
22 pages |
| Authors:
Mark B. Mitchell; CLARK ATLANTA UNIV GA
|
| The achievements realized during the course of this project provide an important alternative method for mitigating the effects of the exposure of personnel and systems to chemical warfare agents and other toxic organic compounds. The research program that was developed built upon earlier results achieved in the room temperature oxidative decomposition of a chemical warfare agent simulant, dimethyl methylphosphonate (DMMP), on solid reactive adsorbents and examined ways of improving those ... |
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| Development of a Tumor Histologic-Specific, Nano-Encapsulated Contrast for Enhancing Magnetic Resonance Imaging of Prostate Cancer |
01-Apr-2008 |
15 pages |
| Authors:
Joel W Slaton; MINNESOTA UNIV MINNEAPOLIS
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| Imaging of both metastatic and localized prostate cancer (CaP) remains a challenge. Our collaborators at GeneSegues, Inc. have developed the nanocapsule, a novel technology that, when coated with antibodies against specific cell types, is capable of delivering large cargos intracellularly into these specific cells. This project proposes to use nanocapsules to carry a contrast agent to human CaP cells growing in mice to enhance MR detection of cancer. Our work ... |
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| Covalent Percolation and Gold Templating of Carbon NanoTubes Network in Polymer Nanocomposites for Novel Mechanical, Electrical, and Optical Properties. Taiwain - US AFOSR Nanoscience Initiative |
26 MAR 2008 |
71 pages |
| Authors:
Arnold C. Yang; NATIONAL TSING HUA UNIV HSINCHU (TAIWAN) DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The interactions between individual polymer chains with embedded carbon nanotubes (CNTs) in nanocomposites were investigated by using two model polymer systems, polystyrene and poly(phenylene oxide) representing respectively the ductile and brittle polymers, with surface-grafted multiwalled CNTs. |
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| RHEEDAX Induced X-ray Fluorescence Analysis System for Oxide MBE |
MAR 2008 |
3 pages |
| Authors:
Hadis Morkoc; VIRGINIA COMMONWEALTH UNIV RICHMOND SCHOOL OF ENGINEERING
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| A total reflection x-ray fluorescence spectroscopy system excited with an electron gun of reflection high-energy electron diffraction tool (RHEED-TRAXs) for in Situ material characterization has been designed, components have been purchased, and the tool has been assembled and installed on a Riber 3200 molecular-beam epitaxy system customized for oxide growth. |
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| Effects of Environment on Creep Behavior of Nextel 720/Alumina-Mullite Ceramic Composite at 1200 deg C |
MAR 2008 |
117 pages |
| Authors:
Christopher L. Genelin; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The creep behavior of an oxide-oxide ceramic matrix composite (CMC) was investigated at 1200 deg C in Laboratory air, in steam and in argon. The composite consisted of a porous alumina-mullite matrix reinforced with laminated, woven mullite/alumina (Nextes/720) fibers. The composite had no fiber coating and relied on its porous alumina/mullite matrix for flaw tolerance. Tensile stress-strain behavior was investigated and the tensile properties were measured at 1200 deg C ... |
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| Molecular Modeling of High-Temperature Oxidation of Refractory Borides |
FEB 2008 |
9 pages |
| Authors:
Ju Li; OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS
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| Refractory diboride with silicon carbide additive has a unique oxide scale structure with two condensed oxide phases (solid + liquid), and demonstrates oxidation resistance superior to either monolithic diboride or silicon carbide. We rationalize that this is because the silica-rich liquid phase can retreat outward to remove the high SiO gas volatility region, while still holding onto the zirconia skeleton mechanically by capillary forces, to form a "solid pillars, liquid ... |
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| Biomineralized 3-D Nanoparticle Assemblies with Micro-to-Nanoscale Features and Tailored Chemistries |
07-Jan-2008 |
30 pages |
| Authors:
Ken H Sandhage; Jennifer A Lewis; GEORGIA INST OF TECH ATLANTA SCHOOL OF MATERIALS SCIENCE AND ENGINEERING
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| This collaborative research project has focused on the integrated use of robust biomimetic or biological silica assembly processes with shape-preserving chemical conversion reactions to produce freestanding 3-D structures with selectable microscale morphologies, nanoscale features, and tailored, non-silica chemistries. Biomimetic 3-D silica structures have been synthesized through Direct-Write Assembly using polyamine-based inks, followed by templated conformal silicification. With proper selection of ink composition and silicification conditions, robust silica structures were formed ... |
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| Molecular Beam Epitaxy on Gas Cluster Ion Beam Prepared GaSb Substrates: Towards Improved Surfaces and Interfaces |
14 DEC 2007 |
9 pages |
| Authors:
Kannan Krishnaswami; Shivashankar R. Vangala; Helen M. Dauplaise; Lisa P. Allen; Gordon Dallas; Daniel Bakken; David F. Bliss; William D. Goodhue; AIR FORCE RESEARCH LAB HANSCOM AFB MA SENSORS DIRECTORATE
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| We report results of a surface modification process for (100) GaSb using gas cluster ion beams(GCIB) that removes chemical mechanical polish (CMP) induced surface damage and replaces the native oxide with an engineered surface oxide, the composition of which depends on the reactive gas employed. X-ray photoelectron spectroscopy of O2-, CF4/O2-, and HBr-GCIB surface oxides is presented indicating the presence of mixed Ga- and Sb-oxides, with mostly Ga-oxides at the ... |
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| Development of In Situ Infrared Spectroelectrochemical Techniques: Application to Lithium Intercalation Reactions in Electrode Materials |
09 OCT 2007 |
10 pages |
| Authors:
Roger Frech; OKLAHOMA UNIV NORMAN
|
| We developed an in situ IR transmission electrochemical cell, which was initially used to study lithium intercalation in a phospho-olivine LixFePO4 cathode. We had previously characterized vibrational spectrum of this material as part of a preliminary study. The transition between LiFePO4 and FePO4 could easily be followed in the in situ spectra. An industrially available coin cell was modified to facilitate routine in situ Raman measurements of lithium batteries. Available ... |
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| Novel Galvanic Corrosion Inhibitors: Synthesis, Characterization, Fabrication and Testing |
30 SEP 2007 |
27 pages |
| Authors:
Issifu I. Harruna; CLARK ATLANTA UNIV GA
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| In materials strategy, the Department of the Navy is the first to consider the development of novel anti-corrosion inhibitors. Thus we proposed to develop novel corrosion inhibitors based on polymer metallocomplex composite materials. These new materials can cut off the electron transfer path via the polymer metallocomplexes. Bipyridine-based polymerizable ligand monomers were synthesized starting from 4,5-diazatluoren-9-one (1). The copolymers of the polymerizable methacrylate-type monomer with styrene, methyl methacrylate, and butyl ... |
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| Multifunctional Oxide Films for Advanced Multifunction RF Systems |
14 SEP 2007 |
33 pages |
| Authors:
Volker D. Heydemann; PENN STATE ELECTRO-OPTICS CENTER FREEPORT PA
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| The Electro-Optics Center of the Pennsylvania State University procured and established a custom-designed molecular beam epitaxy (MBE) system and commenced growth of oxide (TiO2, STO, BTO, BST and MgO) and III-nitride (AIN, GaN) thin films, The growth parameters and layer properties of these films were investigated by various in-situ and ex-situ characterization techniques under the aspect of developing a AIGaN HEMT epitaxy process, a BST varactor epitaxy process and aiding ... |
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| Novel Epitaxy Between Oxides and Semiconductors - Growth and Interfacial Structures |
16 MAY 2007 |
33 pages |
| Authors:
Minghwei Hong; NATIONAL TSING HUA UNIV HSINCHU (TAIWAN) DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The cubic gamma-Al2O3 and Si have significantly different atomic structures and lattice constants. The lattice constant of γ-Al2O3 is 7.91? and that of Si is 5.42 ?. Matching the two lattices over a unit cell dimension will result in a greater than 30% lattice mismatch. It is intriguing that a highly ordered epitaxial growth was obtained in an unusually large mismatch for a hetero-epitaxial system. High-quality single-crystal Sc2O3 films a ... |
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| Remote Measurement of High Temperatures in the Presence of a Strong Magnetic Field |
07 MAY 2007 |
50 pages |
| Authors:
Scott F. Lord; NAVAL ACADEMY ANNAPOLIS MD
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| The environment inside a railgun makes conventional temperature sensing techniques ineffective. Large time-varying magnetic fields induce noise into sensors with electrical connections. The high rate of change of temperature requires a fast thermal response and a fast sampling rate. Finally, the intense heat generated requires a sensor that is thermally stable over a large range of temperatures. To overcome such environmental challenges, this project utilized an interferometric technique where the ... |
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| Effects of Temperature and Environment on Creep Behavior of an Oxide-Oxide Ceramic Matrix Composite |
MAR 2007 |
267 pages |
| Authors:
Jason C. Braun; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| This research investigated the creep behavior of an N720/Al203 composite. The composite consists of a porous alumina matrix reinforced with laminated, woven mullite/alumina fibers (NextelTM 720). This ceramic matrix composite (CMC) has no fiber coating and relies on the porous matrix for flaw tolerance. The tensile stress-strain behavior was investigated and the tensile properties measured in the 800-1100 ?C temperature range. Tensile creep behavior was examined at 1000 and 1100 ... |
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| Fabrication of Highly Ordered Anodic Aluminium Oxide Templates on Silicon Substrates |
2007 |
6 pages |
| Authors:
A. Yin; M. Tzolov; D. Cardimona; L. Guo; J. Xu; BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING
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| The controlled fabrication of highly ordered anodic aluminium oxide (AAO) templates of unprecedented pore uniformity directly on Si, enabled by new advances on two fronts -- direct and timed anodisation of a high-purity Al film of unprecedented thickness (50 micrometres) on Si, and anodizing a thin but pre-textured Al film on Si, has been reported. To deposit high-quality and ultra-thick Al on a non-compliant substrate, a prerequisite for obtaining highly ... |
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| Numerical 3D Model for Thermal Integration of 20W Methanol Reformer |
01 NOV 2006 |
5 pages |
| Authors:
N. E. Blackwell; D. R. Palo; ARMY COMMUNICATIONS-ELECTRONICS RESEARCH DEVELOPMENT AND ENGINEERING CENTER FORT BELVOIR VA
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| Collaborative U. S - Army and U. S. Department of Energy efforts have developed advanced methanol reforming capabilities to enhance production of hydrogen for soldier portable fuel cell systems. Application of advanced numerical techniques combined with empirical data from iterative breadboard measurements has provided the US Army with an 8.5x2xO.8 cm 20W methanol reformer for Future Force Warrior and Future Combat Systems. Fuel cell technology development is being pursued around ... |
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| The Present State of Amperometric Nanowire Sensors for Chemical and Biological Detection |
OCT 2006 |
48 pages |
| Authors:
M. H. Ervin; S. J. Kilpatrick; C. Lombardo; B. M. Nichols; A. C. Perrella; A. E. Wickenden; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
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| This report reviews the research in chemical sensing at the nanometer scale using amperometric detection focusing on publications from January 2004 to September 2005. The devices discussed fall into two categories: chemresistors and chemFETs. In either configuration, the number of carriers available in the channel, and hence the device's transconductance, changes as a function of analyte exposure. Devices based on inorganic nanowires (specifically limited to metal oxides and silicon), conductive ... |
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| On the Structure of Holographic Polymer-Dispersed Polyethylene Glycol (Postprint) |
OCT 2006 |
11 pages |
| Authors:
Michael J. Birnkrant; Hilary K. McWilliams; Christopher Y. Li; Lalgudi V. Natarajan; Vincent P. Toodiglia; Richard L. Sutherland; Pamela F. Lloyd; Timothy J. Bunning; DREXEL UNIV PHILADELPHIA PA
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| Holographic polymerization (H-P) has been used to fabricate polymer-dispersed liquid crystals and pattern inert nanoparticles. In this article, one-dimensional grating structures of Norland resin and polyethylene glycol (PEG) were achieved using the H-P technique. Both reflection and transmission grating structures were fabricated. The optical properties of the reflection grating structures (also known as Bragg reflectors, BRs) are thermosensitive, which is attributed to the formation and crystallization of PEG crystals. The ... |
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| Contact Resistance and Stability Analysis of Oxide-Based Thin Film Transistors |
19 SEP 2006 |
111 pages |
| Authors:
Celia M. Hung; OREGON STATE UNIV CORVALLIS DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| This thesis focuses on 2 aspects of oxide-based thin-film transistors (TFTs), contact resistance and instability assessment. Determination of the contact resistance of indium tin oxide (ITO) on two wide-band gap semiconductors, zinc oxide (ZnO) and indium gallium oxide (IGO), is attempted and the effects of contact resistance on device performance is investigated. Both transistor and transfer length method structures are used and 3 material systems are employed: ZnO on SiO2, ... |
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| Atomically Smooth Epitaxial Ferroelectric Thin Films for the Development of a Nonvolatile, Ultrahigh Density, Fast, Low Voltage, Radiation-Hard Memory |
31 JUL 2006 |
7 pages |
| Authors:
C. H. Ahn; YALE UNIV NEW HAVEN CT GRANT AND CONTRACT ADMINISTRATION
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| The goal of this research is to fabricate atomically smooth, single crystalline, complex oxide thin film nanostructures for use in a nonvolatile, ultrahigh density, fast, low voltage, radiation-hard memory. For this work, we use complex oxide materials, which possess rich electronic phase diagrams, encompassing metallic, insulating, antiferromagnetic, and ferromagnetic behavior. Complex oxides can also exhibit ferroelectricity, which is characterized by the presence of a non-volatile spontaneous polarization field that is ... |
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| Fabrication and Characterization of Electric Field - Induced Resistive Sensor at the end of Scanning Probe Tip |
27 JUL 2006 |
6 pages |
| Authors:
Hyunjung Shin; KOOKMIN UNIV SEOUL (KOREA SOUTH) SCHOOL OF ADVANCED MATERIALS ENGINEERING
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| Fabrication and Characterization of Electrical Field were investigated to develop induced Resistive Sensor at the end of Scanning Probe Tip. The measurement and visual observation of doping profile were performed on Kelvin Prove Force Microscopy (KPFM) & Scanning Nonlinear Dielectric Microscopy (SNDM). NiO Film was fabricated and characterized for Memory Switching applications. Last, effects of Surface Treatment on Work Function & in-plane conductivity of ITO (Indium Tin Oxide) Thin Films ... |
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| Effect of Environment on Creep Behavior of an Oxide/Oxide CFCC with 45 deg. Fiber Orientation |
JUN 2006 |
145 pages |
| Authors:
Gregory T. Siegert; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Aerospace applications require materials capable of maintaining superior mechanical properties while operating at high temperatures and oxidizing environments. Nextel(trademark) 720/A (N720/A), an oxide/oxide ceramic matrix composite (CMC) with a porous alumina matrix was developed specifically to provide improved long-term properties and performance at 1200 deg C. This research evaluated the creep behavior of N720/A with a plus or minus 45 deg fiber orientation at 1200 deg C in: laboratory air, ... |
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| Effects of Frequency and Environment on Fatigue Behavior of an Oxide-Oxide Ceramic Matrix Composite at 1200 Deg. C |
JUN 2006 |
118 pages |
| Authors:
Griffin Hetrick; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Advances in aeronautical engineering in the 21st century depend upon materials that can perform well in extreme environments such as high temperatures and oxidizing conditions. Nextel(Trademark)720/Alumina (N720/A) is an oxide/oxide ceramic matrix composite with a porous alumina matrix that has been identified as a candidate material for such applications. This research investigated the effects of frequency on fatigue response of N720/A at 1200C in both air and steam environment. Prior ... |
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| Oxide Films RF Applications |
JUN 2006 |
11 pages |
| Authors:
Marek Skowronski; P. Salvador; CARNEGIE-MELLON UNIV PITTSBURGH PA OFFICE OF SPONSORED RESEARCH
|
| TiO2 films were grown using a reactive molecular beam epitaxy system equipped with high-temperature effusion cell for Ti and ozone. The growth mode, characterized in-situ by reflection high-energy electron diffraction (RHEED), as well as the phase assemblage, structural quality, and surface morphology, characterized ex-situ by X-ray diffraction and atomic force microscopy (AFM), depended on the choice of substrate, growth temperature, and ozone flux. Films deposited on (100) surfaces of SrTiO3, ... |
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| Development Of Electro-Spark Alloying (ESA) And Thermo-Reactive Electro-Spark Surface Strengthening (TRESS) Technologies And Set Of Equipment With Attachments For Mechanization |
11 MAY 2006 |
18 pages |
| Authors:
Evgeny A. Levashov; MOSCOW INST OF STEEL AND ALLOYS (USSR)
|
| This report results from a contract tasking Moscow State Institute of Steel and Alloys (Technological University) as follows: The main goal of the project is to develop advanced ESA and TRESS coating technologies for application on Ti and superalloys substrates to resist high-cycle fatigue failure initiated at the blade roots. The bar and disc electrodes will be manufactured by self-propagating high temperature synthesis (SHS) method. Mechanical activation for systems with ... |
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| Silver Diffusion and High-Temperature Lubrication Mechanisms of YSZ-Ag-Mo Based Nanocomposite Coatings (Preprint) |
MAY 2006 |
43 pages |
| Authors:
J. J. Hu; C. Muratore; A. A. Voevodin; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| Yttria-stabilized zirconia (YSZ) nanocomposite coatings consisting of silver and molybdenum were produced by a hybrid process of filtered vacuum arc, magnetron sputtering and pulsed laser depositions for tribological investigations at different high temperatures. The microstructure of the coatings was determined by X-ray diffraction and transmission electron microscopy. The friction coefficients were measured using a high-temperature ball-on-disk tribometer at 25 to 700C. The coatings with 24 at.% Ag and 10 at.% ... |
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| A Comparison of Bulk Precipitated Cerium Oxide Powders and Cerium Conversion Coatings and the Influence of Hydrogen Peroxide on Their Formation (Preprint) |
MAR 2006 |
23 pages |
| Authors:
S. A. Hayes; P. Yu; T. J. O'Keefe; J. O. Stoffer; MISSOURI UNIV-ROLLA
|
| To better understand the role of hydrogen peroxide in the formation of cerium conversion coatings and precipitates, hydrated cerium oxide/hydroxide materials obtained from aqueous solutions have been characterized by thermogravimetic methods, X-ray diffraction, and scanning electron microscopy. Powders were prepared by precipitation with sodium hydroxide from cerium (III) chloride solutions using either hydrogen peroxide or oxygen sparging to oxidize Ce(III) species to Ce(IV) species. Cerium conversion coatings were deposited on ... |
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| Production of Lunar Oxygen Through Vacuum Pyrolysis |
26 JAN 2006 |
71 pages |
| Authors:
John Matchett; GEORGE WASHINGTON UNIV WASHINGTON DC SCHOOL OF ENGINEERING AND APPLIED SCIENCE
|
| Increasing efficiency of future space exploration will require that missions utilize non-terrestrial resources for propellant manufacture. The vacuum pyrolysis method of oxygen production from lunar regolith presents a viable option for in situ propellant production because of its simple operation involving limited resources from earth. Lunar regolith, the fine layer of pulverized rock across the entire lunar surface, is composed of approximately forty percent oxygen in the form of metal ... |
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| Effects of Environment on Creep Behavior of Two Oxide-Oxide Ceramic Matrix Composites at 1200 degs C |
SEP 2005 |
201 pages |
| Authors:
Pavlos A. Koutsoukos; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Previous studies by the advisor and graduate students examined creep behavior of the Nextel720/Alumina CMC in air and in 100% steam environments at 1200 and 1330 deg C. Results showed that while this oxide/oxide system exhibits an exceptionally high fatigue limit at 1200 deg C it also experiences substantial strain accumulation under sustained loading conditions. Furthermore, these earlier investigations revealed a significant degrading effect of 100% steam environment on material ... |
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| Mechanisms of Metal Release From Contaminated Coastal Sediments |
SEP 2005 |
240 pages |
| Authors:
Linda H. Kalnejais; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| The fate of trace metals in contaminated coastal sediments is poorly understood, yet critical for effective coastal management. The aim of this thesis is to investigate and quantify the mechanisms leading to the release of silver, lead and copper across the sediment-water interface. Two contrasting sites were investigated, a heavily contaminated site in Boston Harbor and a less impacted, offshore site in Massachusetts Bay. High-resolution porewater and solid phase samples ... |
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| Self Contained Fuel System for Solid Oxide Fuel Cell |
18 AUG 2005 |
10 pages |
| Authors:
Louis G. Carreiro; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A power source for an unmanned undersea vehicle with increased energy density is described that employs a self-contained fuel system to address carbon dioxide evolution. A solid oxide fuel cell serves as the power source in the self- contained fuel system. In combination with the solid oxide fuel cell, the system comprises a chemical composite that is combined with water to create both a hydrocarbon fuel for the solid oxide ... |
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| High-Efficiency Heterojunction Photovoltaic Devices by Block Copolymer Nanotemplates |
AUG 2005 |
24 pages |
| Authors:
Jin K. Kim; Jeong I. Lee; Jeong A. Jang; Unyong Jeong; POHANG UNIV OF SCIENCE AND TECHNOLOGY (KOREA SOUTH) DEPT OF CHEMICAL ENGINEERING
|
| Ultra high density arrays of conducting poly(pyrrole) (Ppy) and poly (3-hexyl thiopene) (P3HT) nanowires with diameters of 10~25 nm were prepared on indium-tin oxide coated glasses (ITO) by electropolymerization of the monomers inside nanoporous templated prepared by block copolymers. These high density arrays of conducting polymer nanowires could be used as P-type materials for photovoltaic devices. It was observed that even after the PS matrix was removed, the free standing ... |
|
| Synthesis and Characterization of Fluoropropyl POSS |
JUL 2005 |
28 pages |
| Authors:
Wade Grabow; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Fluorinated polyhedral oligomeric silsesquioxanes (POSS) are under investigation for potential lubricant applications. POSS compounds are characterized by a rigid, inorganic core consisting of silicon and oxygen, offering properties similar to those of ceramics; in addition to organic functional groups protruding from the inorganic core, offering organic functionality. Synthesis of POSS generally yields cage mixtures giving varying confirmations of the POSS (Si-O) core denoted by the number of silicon atoms present ... |
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| Syntheses of 1,2,3,4-Tetrazine Di-N-oxides, Pentazole Derivatives, Pentazine Poly-N-oxides, and Nitroacetylenes |
30 JUN 2005 |
51 pages |
| Authors:
H. Shechter; M. Venugopal; D. Srinivasulu; OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS
|
| Study has been initiated of practical synthesis and the chemistry of 1) 1,2,3,4-tetrazines and their products, 2) 5,6-distubstituted- 1,2,3,4-tetrazine 1,3-di-N-oxides, 5,6-diketo- 1,2,3,4-tetrazine I ,3-di-N-oxide and its derivatives, isometric 1,2,3,4,5,6,7,8- octazanaphthalene tetroxides (DTTO and IsoDTTO), various substituted benzotetrazine 1,3-di -N-oxides and their transformations, isomeric furoxanotetrazine 1,3-di-N-oxides, furazanotetrazine 1,3-di-N-oxide, (FTDO), 5,6-(1 ,2,3-triazolo)-1 ,2,3,-tetrazine 1,3-di-N-oxides, and various 1- nitroacetylenes and dinitroacetylenes and their respective precursors and derivatives. The various synthetic routes studied have ... |
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| Electrochemical Study of Corrosion Phenomena in Zirconium Alloys |
JUN 2005 |
134 pages |
| Authors:
Nicole M. Treeman; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF NUCLEAR ENGINEERING
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| Shadow corrosion of zirconium alloy fuel cladding in BWR environments, the phenomenon in which accelerated corrosion is experienced when the cladding surface is in close proximity to other metals, has become a potentially life-limiting issue for BWR fuel. Recent results from experimentation at MIT, Halden, and Studvik suggest that a galvanic coupling drives the phenomenon between the cladding and the adjacent material. However, the actual processes involved are not understood. ... |
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| Matrix-Enabled Damage Tolerance in Oxide CFCCs |
JUN 2005 |
59 pages |
| Authors:
Francis W. Zok; Carlos G. Levi; Robert M. McMeeking; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
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| The program has focused on the mechanics of deformation and fracture of a family of porous-matrix all-oxide continuous fiber ceramic composites (CFCCs). The activities have led to substantive developments in the mechanistic understanding of: (1) mechanical properties and thermal stability of porous mullite/alumina matrices; (2) strength, fracture resistance and notch sensitivity of porous-matrix composites; and (3) stability and performance of oxide composites in gas turbine combustion environments. Models to describe ... |
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| A Comparative Study of the Structure-Property Behavior of Highly Branched Segmented Poly(Urethane Urea) Copolymers and Their Linear Analogs |
2005 |
12 pages |
| Authors:
Jignesh P. Sheth; Serkan Unal; Emel Yilgor; Iskender Yilgor; Frederick L. Beyer; Timothy E. Long; Garth L. Wilkes; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CHEMICAL ENGINEERING
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| The solid-state structure-property behavior of highly branched segmented poly(urethane urea) (PUU) copolymers and their linear analog was investigated. A limited study of their solution rheological behavior was also undertaken. The linear PUUs were synthesized by the twostep prepolymer method, whereas the oligomeric A2CB3 methodology was utilized to synthesize the highly branched materials. The soft segments (SS) were either poly(tetramethylene oxide) (PTMO) or poly(propylene oxide) (PPO). All copolymers utilized in this ... |
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| Quantification of Discrete Oxide and Sulfur Layers on Sulfur-Passivated InAs by XPS |
2005 |
11 pages |
| Authors:
D. Y. Petrovykh; J. M. Sullivan; L. J. Whitman; MARYLAND UNIV COLLEGE PARK DEPT OF PHYSICS
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| The initial quality and stability in air of InAs(001) surfaces passivated by a weakly-basic solution of thioacetamide (CH3CSNH2) is examined by XPS. The S-passivated InAs(001) surface can be modeled as a sulfur-indium-arsenic layer-cake structure, such that characterization requires quantification of both arsenic oxide and sulfur layers that are at most a few monolayers thick. This thickness range complicates the quantitative analysis because neither standard submonolayer nor thick-film models are applicable. ... |
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| Carbothermal Reduction Synthesis and Structural Evolution of Nanocrystalline Ultra High Temperature Carbides |
DEC 2004 |
63 pages |
| Authors:
Michael D. Sacks; GEORGIA TECH RESEARCH CORP ATLANTA
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| Zirconium carbide (ZrC) and hafnium carbide (HfC) powders were produced by the carbothermal reduction reaction of carbon and the corresponding metal oxide (ZrO2 and HfO2, respectively). Solution-based processing was used to achieve a fine-scale (i.e., nanometer-level) mixing of the reactants. The reactions were substantially completed at relatively low temperatures (<1500 C) and the resulting products had small average crystallite sizes (^5O-l3O nm). Dry-pressed compacts prepared using ZrC-based powders with ^100 ... |
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| Ceria Based Nano-Scale Catalysts For Water-Gas Shift (WGS) Reaction |
DEC 2004 |
6 pages |
| Authors:
Deryn Chu; Ivan C. Lee; Ranjan K. Pati; Sheryl H. Ehrman; ARMY RESEARCH LAB ADELPHI MD
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| This paper describes our research efforts towards the preparation of high surface area ceria oxide (CeO2) containing catalysts for fuel processing and therefore for fuel cells applications. In the present work, we present a simple. single step flame synthesis method to prepare high surface area ceria based fuel reformation catalysts using aqueous solutions of metal acetate precursors. The specific surface areas of the synthesized powders are in the range of ... |
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| Issues of Compatibility Between Nanomaterials and Aluminum Scanning Electron Microscopic Mounts |
DEC 2004 |
18 pages |
| Authors:
Donovan Harris; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Aluminum mounts are ubiquitously present in scanning electron microscope (SEM) laboratories. They are an inexpensive light material with good conductivity properties, and are generally compatible with conductive adhesive products. In the course of using aluminum mounts to examine nanoscale materials, some compatibility issues were revealed. One limiting issue was charge conduction. Nanoscale materials can be a more efficient conductor of electrons than the aluminum mount with its layer of oxides. ... |
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| Laser Surface Preparation for Adhesive Bonding II. Task Order 5TS5703D035S |
DEC 2004 |
69 pages |
| Authors:
Craig T. Walters; CRAIG WALTERS ASSOCIATES DUBLIN OH
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| For several years, research has been undertaken for the U.S. Air Force to assess the utility of pulsed laser beams in the cleaning of surfaces without the use of solvents or abrasives. Initial efforts led to the development of a prototype laser-based cleaning system that could effectively remove paint, contaminants, and oxides from metal surfaces such as aluminum, stainless steel, and titanium. In follow-on research, the basic laser cleaning concepts ... |
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