| Dynamic and Cyclic Fatigue Testing of Esthetic Single Tooth Implant Restorations |
07 JAN 1999 |
62 pages |
| Authors:
William E. Dinse; TEXAS UNIV HEALTH SCIENCE CENTER AT SANANTONIO
|
 | Conventional single tooth implant restorations can be unesthetic at the gingival level if they exhibit metal collars or are limited by the cylindrical shapes of the implants. Important mechanical properties of novel restorations with more esthetic features are unknown. The purpose of this investigation was to determine the elastic limit and mode of failure for four types of esthetic single tooth implant restorations and to determine the fatigue performance of ... |
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| Parallel Contact Patterning Using Nanochannel Glass |
05 JAN 1999 |
|
| Authors:
Ronald J. Tonucci; Douglas H. Pearson; DEPARTMENT OF THE NAVY WASHINGTON DC
|
 | The present invention is a method for modifying a substrate in a predetermined pattern, comprising the steps of: (a) applying a material to the face of an etched nanochannel glass (NCG), where this face has a pattern of channels corresponding to the predetermined pattern, and (b) contacting the substrate with the etched NCG face having applied material, under conditions for transferring the material to the substrate, |
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| Engineering and Design: Compilation of Concrete Aggregate and Stone RIPRAP Test Data |
01 JAN 1999 |
7 pages |
| Authors:
CORPS OF ENGINEERS WASHINGTON DC
|
| This regulation prescribes the procedures for the continuing compilation and distribution of test data on concrete aggregates and stone riprap from sources within the continental United States and Alaska. |
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| Synthesis of Ceramics from Solutions: Functionally Graded Composites, Nanocomposites and Single Crystal Thin Films; Annual Technical Reports 12 Through 16 with a Summary |
JAN 1999 |
80 pages |
| Authors:
Fred F. Lange; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| This program has emphasized two topics: (1) the crystallization of metastable, solid-solution structures, their partitioning into equilibrium structures and compositions, and the role of the metastable phase and its partitioning on forming unique, nanometer microstructures important to the mechanics of structural ceramics and their composites, and (2) the formation of single crystal thin films via spin coating single crystal substrates with solution precursors. Results for the first topic are new, ... |
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| Toughening of Heterogeneous Ceramics |
JAN 1999 |
14 pages |
| Authors:
W. A. Curtin; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIENCE AND MECHANICS
|
| The goal of this program is to develop accurate micromechanical models of the damage mechanisms in fiber-reinforced composites, so as to provide predictive models of macroscopic composite behavior. Such predictive models clearly highlight the key controlling mechanisms of various stages of deformation and to quantitatively relate the constitutive properties of the fibers, matrix, and interface to the overall deformation of the composite. The understanding ... |
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| A Ceramic Armor Material Database |
JAN 1999 |
240 pages |
| Authors:
T. J. Holmquist; A. M. Rajendran; D. W. Templeton; K. D. Bishnoi; TACOM RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
|
| This report compiles and documents a Ceramic Armor Material Database. Experimental data obtained from numerous journals and conference proceedings, by researchers of various disciplines, covering over thirty years are documented in this report. The data include nine different ceramic materials. The ceramics are Silicon Carbide, Boron Carbide, Titanium Diboride, Aluminum Nitride, Silicon Nitride, Aluminum Oxide (85% pure), Aluminum Oxide (high purity), Tungsten Carbide and Glass. For each ceramic material, experimental ... |
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| Intergranular and Interphase Boundaries in Materials (IIB |
1999 |
831 pages |
| Authors:
Pavel Lejcek; Vaclav Paidar; CZECH ACADEMY OF SCIENCES PRAGUE INST OF PHYSICS
|
| The 9th International Conference on Intergranular and Interphase Boundaries in Materials (iib'98) held on 6-9 July 1998 in Prague, Czech Republic, represents a successful continuation of the series of this Conference starting by the first meeting in Saint Etienne, France, in 1975. Following the scope of the preceding meetings, this Conference was focused on atomic level modeling of interfaces, structural and chemical characterization of internal ... |
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| Fundamental Structure-Property Relationships for High-Temperature Ceramic Composites |
1999 |
9 pages |
| Authors:
Elizabeth C. Dickey; KENTUCKY UNIV LEXINGTON DEPT OF MATERIALS AND SCIENCE ENGINEERING
|
| Directionally-solidified oxide eutectics such as alumina-YAG and alumina-zirconia show promise as high-temperature structural materials because of their high temperature strength and creep resistance. 1-5 Compatibility constraints at the internal interfaces between the two constituent phases can lead to residual stresses upon thermal cycling and elastic interaction stresses under applied loads. The magnitudes and distributions of these stresses have important ramifications for the mechanical behavior of the composites. Here we investigate ... |
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| AASERT Student Research on Non-Oxide Structural Ceramics - Alloy Design for Improved Sinterability and Mechanical Performance |
31 DEC 1998 |
6 pages |
| Authors:
I-Wei Chen; MICHIGAN UNIV ANN ARBOR
|
| The objective of this research is to design micro structures in non- oxide ceramics to improve their mechanical performance and sinter ability. Silicon nitride and silicon carbide with similarly controlled micro structures and residual stress distribution have been investigated. The grant was initiated in 1996. The AASERT student supported by the grant, Anatoly Rosenflanz, discovered an in-situ toughened a'-SiAlON and a patent was filed. This research ... |
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| Infrared Transparent Selenide Glasses |
08 DEC 1998 |
|
| Authors:
Barry B. Harbison; Jasbinder S. Sanghera; John A. Moon; Ishwar D. Aggarwal; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A selenide glass with improved mechanical and optical properties such as extended transmission in the infrared region of radiation having wavelengths beyond 15 microns; Tg in the region of 363 degrees-394 degrees C; and thermal stability of 85 degrees-145 degrees C. based on the difference between T(g) and T(x), comprising, on mol basis, 20-70% germanium selenide, 0.5-25% gallium selenide, indium selenide or mixtures thereof; and 5-5O% of at least one ... |
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| The Johnson-Holmquist Ceramic Model as used in LS-DYNA2D |
DEC 1998 |
|
| Authors:
G. McIntosh; DEFENCE RESEARCH ESTABLISHMENT VALCARTIER (QUEBEC)
|
| A constitutive model for ceramics by Johnson and Holmquist has been incorporated and validated in the finite element computer program LS-DYNA2D. Using experimental data acquired at DREV, parameters for high density ceramics (around 98% theoretical maximum density) have been established. The effect of varying some of the parameters on the calculated depths of penetration into semi-infinite targets and the ballistic limits of armor has been investigated. |
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| Bond Variability of Glass-Fiber-Reinforcing-Plastic Reinforcement in Concrete |
DEC 1998 |
414 pages |
| Authors:
Joseph P. Hanus; MINNESOTA UNIV MINNEAPOLIS
|
| This report summarizes an experimental program that investigated the bond variability of glass-fiber-reinforced-polymer (GFRP) reinforcement in concrete. The variables in the study were manufacturer (Marshall Industries Composites, Inc. M1 and Corrosion Proof Products/Hughes Brothers M2), bar size (No. 5 and 6), cover (2 and 3 bar diameters), and embedment length (10 through 47 in.). Tensile tests were also performed on the GFRP rebar for comparison to bond tests that exhibited ... |
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| Effect of Fiber-Reinforced Plastic Strength Properties on the Ballistic Performance of Ceramic Composite Armor |
NOV 1998 |
24 pages |
| Authors:
James F. Mackiewicz; Gary Proulx; ARMY SOLDIER AND BIOLOGICAL CHEMICAL COMMAND NATICK MA SOLDIER SYSTEMS CENTER
|
| This report provides detailed results of an investigation of the effect of Fiber-Reinforced Plastic (FRP) strength properties on ceramic composite armor ballistic performance. FRP laminates ranging from 5.3% - 19.5% resin content produced a range of weak to relatively strong panels in term of flexural strength, shear strength and elastic modulus. The low resin and corresponding low strength laminates yielded the most efficient armor systems when tested in conjunction with ... |
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| Silicon-Based Nanostructural Ceramics Derived From Polymer Precursors: Development of Processing, Structure & Property Relationships |
15 OCT 1998 |
70 pages |
| Authors:
Wayde R. Schmidt; UNITED TECHNOLOGIES CORP HARTFORD CT
|
| This research program built on the knowledge gained under past AFOSR support and focused on developing additional basic understanding of the relationships between ceramic product and corresponding polymer precursor structures, as a function of processing conditions. The primary objectives for this work were to: (1) demonstrate the use of silicon-based polymeric precursors as sources of nanostructured ceramic phases, including SiC, Si3N4, and SiC/AlN solid solutions; and (2) examine the ambient, ... |
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| The Influence of Alloying and Processing on the Microstructure and Properties of Beta-NiAl |
30 SEP 1998 |
429 pages |
| Authors:
M. J. Kaufman; R. Abbaschian; FLORIDA UNIV GAINESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The overall objective of this program was to provide a fundamental understanding of the effects of alloying and processing on the microstructure- property-processing relationships of monolithic b-NiAl. The emphasis was to determine the factors that affect both the low and high temperature compound by studying single crystals, bicrystals and polycrystals of selected alloys. Modeling of the solidification behavior was performed with the goal of understanding better the role of processing ... |
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| Engineering and Design: Cement, Slag, and Pozzolan Acceptance Testing |
30 SEP 1998 |
16 pages |
| Authors:
CORPS OF ENGINEERS WASHINGTON DC
|
| This regulation sets forth policy and responsibilities for acceptance testing of cementitious materials including portland cement, blended cement, pozzolan, and ground granulated blast-furnace slag (hereinafter referred to as slag). |
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| Penetrator Resistance and Target Damage Due to Multiple Impacts upon Granite and Concrete: Joint Experimental, Analytical and Numerical Effoft |
23 SEP 1998 |
39 pages |
| Authors:
Jack Dvorkin; PETROPHYSICAL CONSULTING REDWOOD CITY CA
|
| The overall objective of the proposed research was to fundamentally and quantitatively understand, based on first physical principles, the micromechanics of penetration into and damage accumulation in cemented particulate targets subject to multiple impact. The approach was to integrate experiments, analytical micromechanics, and numerical modeling into a concerted effort. The project was to be conducted jointly with the University of Rhode Island. The Petrophysical ... |
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| A Feasibility Study of Liquid Phase Sinter Forming of a Model Ceramic System |
SEP 1998 |
72 pages |
| Authors:
Jason M. Lloyd; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The feasibility of a new manufacturing process of ceramic materials in which net shaped products are produced via sintering and simultaneously deforming is studied. A suitable model system of SiO2-B2O3 is chosen due to its desirable properties for liquid phase sintering and its ability to be tested under atmospheric conditions. Samples of compacted powder are prepared and characterized via x-ray diffraction and scanning electron microscopy. ... |
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| Performance Criteria for Concrete Repair Materials, Phase II Field Studies |
SEP 1998 |
95 pages |
| Authors:
Peter H. Emmons; Alexander M. Vaysburd; Randall W. Poston; James E. McDonald; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
|
| The study reported herein is part of an overall investigation to develop performance criteria for cement-based materials. Preliminary performance criteria for dimensionally compatible repair materials were proposed in Phase I of the study. Laboratory and field tests to evaluate these criteria were conducted in Phase II of the project. The field-testing program described herein included installation of 12 selected cementitious repair materials in prefabricated repair ... |
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| Extended Abstracts, 11th International Symposium on Non-Oxide & New Optical Glasses, 6-10 September 1998, Sheffield, UK |
SEP 1998 |
598 pages |
| Authors:
SHEFFIELD UNIV (UNITED KINGDOM)
|
| The 11th International Symposium, formerly known as the International Symposium on Non-Oxide Glasses, and held about every two years since 1981, is the premier conference for discussion of the latest developments in synthesis, structure, properties, processing and applications of non-oxide glasses and new optical glasses. An important objective of the Symposium is to bridge the gap between scientific understanding and technical requirements so that the enormous future potential of special ... |
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| High Thermal Conductivity AlN Packages for High-Temperature Electronics |
SEP 1998 |
52 pages |
| Authors:
E. Savrun; C. Toy; M. Sarikaya; SIENNA TECHNOLOGIES INC WOODINVILLE WA
|
| A novel metallization for aluminum nitride substrates and related interconnection materials were investigated for packaging silicon carbide devices for use at temperatures up to 600 deg C. Aluminum nitride substrates were metallized with refractory metals using both thin and thick film metallization techniques. Excellent metallization adhesions (>- 10 ksi) were achieved at low sheet resistivities for both films. Phase diagrams were used to select potential bond pad, die attach and ... |
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| 11TH International Symposium on Non-Oxide & New Optical Glasses |
SEP 1998 |
603 pages |
| Authors:
SHEFFIELD UNIV (UNITED KINGDOM)
|
| The abstracts of the eleventh International Symposium on non-oxide glasses and new optical glasses at Sheffield, UK is presented. |
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| Low Cost, YAG and Mullite Fibers by Continuous Extrusion an Pyrolysis ofMetal Carboxylate Precursors |
31 AUG 1998 |
26 pages |
| Authors:
Robert Svedberg; Michael Vitale; Richard M. Laine; Kean W. Chew; Marcus Weinmann; ADVANCED MODULAR POWER SYSTEMS INC ANN ARBOR MI
|
| Optimal ceramic reinforced CMS's and MMC's are the key to the success of many Air Force programs because of the significant promise these lightweight, high strength materials offer for meeting projected performance and protection requirements for a wide variety of aerospace applications. This Phase I program has explored methods of producing continuous yttrium aluminum garnet (Y3Al5O12) and mullite (3Al2O3.SiO2) fibers. In Task 1, synthesis reactors have been ... |
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| New Developments in High Temperature Ceramics Conference Held in Istanbul, Turkey on August 12-15, 1998 |
27 AUG 1998 |
43 pages |
| Authors:
TECHNISCHE UNIV HAMBURG (GERMANY F R)
|
| The Final Proceedings for New Developments in High Temperature Ceramics, 12 August 1998 to 15 August 1998. This is an interdisciplinary conference. Topics include processing, microstructure design and control and structural ceramics. Includes abstracts of conference presentations. |
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| Autoclaved Aerated Concrete: Shaping the Evolution of Residential Construction in the United States |
14 AUG 1998 |
54 pages |
| Authors:
Steven C. Bukoski; GEORGIA INST OF TECH ATLANTA
|
| Precast Autoclaved Aerated Concrete (AAC) is a proven construction material used in Europe for over 70 years. Introduced to the United States in 1990, construction thus far is limited to commercial and custom borne applications. Premium benefits include energy efficiency and resistance to natural disaster and pests. Despite being the leading residential construction material in Europe and Japan, lumber is the leading material of ... |
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| The Formation of the Second-Order Nonlinearity in Thermally Poled Fused Silica Glass |
07 AUG 1998 |
127 pages |
| Authors:
Thomas G. Alley; NEW MEXICO UNIV ALBUQUERQUE OPTICAL SCIENCES CENTER
|
| This study examines the physics underlying the formation of a second- order nonlinearity through thermal poling in bulk fused silica glass. The technique of thermal poling involves applying a large voltage across the glass at an elevated temperature, and then allowing the glass to cool with voltage applied. Nominally, a nonlinearity is created from a high-field space-charge region that forms within ^ 10 microns of the ... |
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| An Assessment of New Applications for Single-Crystal Piezoelectric Materials |
AUG 1998 |
|
| Authors:
Lisa Veitch; INSTITUTE FOR DEFENSE ANALYSES ALEXANDRIA VA
|
| Piezoelectricity was first discovered by the Curie brothers in 1880. During the 1940s, piezoelectric ceramic materials were first used in commercial devices, and new materials and other applications have continued to develop over the years. Most recently, however, relaxor-based ferroelectric single crystals have been produced. In most cases, these single-crystal material properties, exceed those of conventional piezoelectric ceramics. The purpose of this study was to determine the current commercial and ... |
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| Solid Freeform Fabrication Proceedings (9th) Held in Austin, Texas on August 10-12 1998 |
AUG 1998 |
|
| Authors:
Harris L. Marcus; Joseph J. Beaman; David L. Bourell; Joel W. Barlow; Richard H. Crawford; TEXAS UNIV AT AUSTIN
|
| The Ninth Solid Freeform Fabrication (SFF) Symposium, held at The University of Texas in Austin on August 10-12, 1998, was attended by over 150 national and international researchers. Papers addressed SFF issues in computer software, machine design, materials synthesis and processing, and integrated manufacturing. New sessions on ceramic materials and multiple materials SFF were added to this year's program. The diverse domestic and foreign attendees included industrial users, SFF machine ... |
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| IR Transmitting Rare Earth Gallogermanate Glass-Ceramics |
28 JUL 1998 |
|
| Authors:
Shyam S. Bayya; Barry B. Harbison; Jasbinder S. Sanghera; Ishwar D. Aggarwal; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A glass-ceramic article or composition which has better thermal and physical properties than the competing materials of zinc sulfide, spinel, or magnesium fluoride comprising 2-30 mole percent yttrium oxide and/or rare earth oxide 25-80 mole percent germanium oxide and 5-30 mole percent gallium oxide based on the total moles of yttrium oxide and/or the rare earth oxide, germanium oxide, and gallium oxide; which article is over 80% by volume crystalline. ... |
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| Scandia, Yttria-Stabilized Zirconia for Ultra-High Temperature Thermal Barrier Coatings |
14 JUL 1998 |
|
| Authors:
Robert L. Jones; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A composite structure includes a self-supporting substrate and a thermal barrier coating of zirconia stabilized with scandia and yttria. A method of protecting the surface of a self-supporting substrate from degradation caused by exposure to temperatures above 1200 deg C. includes the step of applying to the surface a coating of zirconia stabilized with scandia and yttria. |
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| Strength and Inelastic Deformation in Shocked Polycrystalline Silicon Carbide |
10 JUL 1998 |
8 pages |
| Authors:
Y. M. Gupta; WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS
|
| The objective of this research project was to quantify the response of shocked ceramics, including strength in the shocked state, to understand the mechanisms governing inelastic deformation at high stresses and high strain- rates in these materials. In-situ, piezoresistance stress gauge measurements were obtained in dense, polycrystalline silicon carbide (SiC) samples subjected to plane wave loading. A significant effort was carried out to ensure a self- consistent analysis of the ... |
|
| 9TH International Conference Intergranular and Interphase Boundaries in Materials, Prague, Czech Republic, 6 - 9 July 1998 |
09 JUL 1998 |
296 pages |
| Authors:
Vaclav Paidar; CZECHOSLOVAK ACADEMY OF SCIENCES PRAGUE INST OF PHYSICS
|
| Compilation of abstracts collected for the conference entitled "9th International Conference; Intergranular and Interphase Boundaries in Materials" held in Prague, Czech Republic, 6 - 9 July 1998. |
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| Performance Enhancement in Ferroelectric Thin Films for Uncooled Infrared Imaging Arrays |
JUL 1998 |
10 pages |
| Authors:
K. R. Udayakumar; H. R. Beratan; C. M. Hanson; RAYTHEON SYSTEMS CO DALLAS TX
|
| The development of high performance monolithic pyroelectric IR detectors requires ferroelectric films of high responsivity and high thermal isolation of self-supporting micromachined structures. In the DARPA-supported IR detector materials program, the ultimate goal is to demonstrate film properties that project to a system-level f/1 NETD of 10 mK for 48.5 micrometers-pixels. This paper will delineate materials and processes engineered towards that objective. Films investigated in this program have been from ... |
|
| European Materials Research Society Spring Meeting Held in Strasbourg, France on 16-19 June 1998. Book of Abstracts |
19 JUN 1998 |
335 pages |
| Authors:
EUROPEAN MATERIALS RESEARCH SOCIETY STRASBOURG (FRANCE)
|
| This document contains abstracts of the various symposiums held as part of the European Materials Research Society Spring Meeting held on 16-19 June 98 in Strasbourg, France. Some of the topics discussed were Light Emission from Silicon; Defects in Silicon: Hydrogen; Thin Films Epitaxial Growth and Nonstructures; Surface Processing; Microsystem Technologies; Rapid Thermal Processing; Ion Implantation into Semiconductors, Oxides and Ceramics; Carbon Based Materials; Nitrides and Related Wide Band Gap ... |
|
| Final Report DARPA Contract Number DAAH01-98-P-R010 (Advanced Cerametrics, Inc.) |
16 JUN 1998 |
3 pages |
| Authors:
Jonathan D. French; ADVANCED CERAMETRICS INC LAMBERTVILLE NJ
|
| This report covers the period between the completion of SBIR Phase I contract # DAA- H01-97-C-R114 and Phase II SBIR contract # DAA-H01-98-C-R107. This effort was expended, in response to contract # DAA-H01-98-P-R010. The general purpose of this work was to begin preparation for the above Phase II SBIR ahead of actual award so that the two year Phase II period could be more effectively ... |
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| Application of Artificial Neural Networks to Ultrasonic Pulse Echo System for Detecting Microcracks in Concrete |
JUN 1998 |
42 pages |
| Authors:
A. Michael Alexander; Richard W. Haskins; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
|
| Concrete deterioration standards containing various levels of microcracks were engineered by adding calcium sulfate to the concrete mixture and curing under moisture at 38 deg. C (100 deg. F). The level of the mircocracks was classified according to the speed of the ultrasonic pulse velocity (UPV) through the specimens using the American Society for Testing and Material (ASTM) C 597 (ASTM 1994c) test method and was found to vary uniformly ... |
|
| Composite Grids for Reinforcement of Concrete Structures |
JUN 1998 |
170 pages |
| Authors:
Plyush K. Dutta; David M. Bailey; Stephen W. Tsai; David W. Jensen; John R. Hayes Jr; CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPAIGN IL
|
| This research investigated a new concept that uses fiber-reinforced plastic (FRP) composite grid to reinforce concrete structural members. Prefabricated two- and three-dimensional FRP grid structures were investigated as a possible alternative to conventional one-dimensional steel reinforcement rods. Currently available commercial grid manufacturing techniques were found to be inadequate due to material flaws, poor fiber volume fraction, and low strength and stiffness. Through laboratory investigations, significant improvements in fiber volume fraction ... |
|
| Mechanical Alloying Processing with Applications to Structural Materials |
JUN 1998 |
10 pages |
| Authors:
Thomas H. Courtney; MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF METALLURGICAL ENGINEERING
|
| Relationships among the synthesis, processing, structure and properties of materials generated through mechanical alloying (MA) or mechanosynthesis are described. Several materials classes: cermets, particulate metal matrix composites (MMC), and tungsten heavy alloys (WHA) have been produced, and their properties and structures evaluated. Niobium carbide and tungsten, carbide cermets can be conveniently generated either through room temperature synthesis (NbC cermets) or by room temperature milling followed by elevated temperature exposure (WC ... |
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| Spray Deposition Processing of Al/SiC MMC Armor Materials and Ta Alloys for Army Applications |
JUN 1998 |
176 pages |
| Authors:
E. J. Lavernia; F. A. Mohamed; CALIFORNIA UNIV IRVINE DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
|
| In this research program, the spray atomization and deposition technique was both experimentally and numerically studied to process ceramic particulate reinforced (including functionally graded reinforcement distributions) A1 alloy metal matrix composites (MMCs) as armor materials and Ta alloys for Army applications such as shaped charged liners and explosively formed projectiles. In this final progress report, the aforementioned experimental and numerical results are described and discussed in five individual sections, which ... |
|
| An Ultraviolet X-Ray Laser Source for Core Level Spectroscopy and Dynamics of Metal Cluster/Ceramic Chemistry |
31 MAY 1998 |
3 pages |
| Authors:
Stephen R. Leone; Veronica M. Bierbaum; COLORADO UNIV AT BOULDER
|
| A titanium sapphire ultrafast laser system was procured and merged with a high repetition rate pulsed valve to produce higher harmonic light output in a rare gas jet. The ultrafast laser system consists of a seed laser, a regenerative amplifier, and a two-pass power amplifier. The system operates' at 2.8 mJ energy per pulse, 75 fs pulse duration, and 1000 Hz repetition rate. Higher harmonics up to 20 eV have ... |
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| Non-Oxide Structural Ceramics - Alloy Design for Improved Sinterability and Mechanical Performance |
12 MAY 1998 |
8 pages |
| Authors:
I. W. Chen; Tseng Ying Tien; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Research on non-oxide structure ceramics including silicon nitride, silicon carbide and titanium diboride has been conducted Multiphase silicon nitride composites with melilite and other high nitrogen content grain boundary phases have been prepared. These composites can be sintered to high density and they show improved oxidation resistance. Mechanical properties have been evaluated and found to compare favorably with other silicon nitride materials. Phase relations have also been delineated for various ... |
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| Modeling Ceramic Defeat Mechanisms and Variations in Ballistic Data |
MAY 1998 |
51 pages |
| Authors:
Nevin L. Rupert; Fred I. Grace; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Bi-element or layered targets have been used to obtain depth-of- penetration (DOP) data so that performance of ceramic materials under ballistic impact can be evaluated. While the data have been particularly useful for ranking ceramics as possible armor candidates, interpretation of the data has been difficult and little insight into the dynamics and mechanisms of the penetration process has been obtained from such data Prior analytical work into the penetration ... |
|
| Thermal Barrier Coatings (les Revetements anti-mur de chaleur) |
APR 1998 |
177 pages |
| Authors:
ADVISORY GROUP FOR AERONAUTICAL RESEARCH AND DEVELOPMENT PARIS (FRANCE)
|
| Thermal barrier coatings are an emerging technology which will enable either an increase in turbine inlet temperatures, or a reduction in the duty temperature of the blades and as a result, an extension of their life-cycle. This Workshop presented the state of the art, gave a description of the existing or emerging technologies, summarized our present knowledge of damage mechanisms, including microstructural, mechanical and thermal aspects, and reported on the ... |
|
| Ice Damage to Concrete |
APR 1998 |
54 pages |
| Authors:
Erland M. Schulson; COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
|
| Concrete is a porous material. When saturated with water and then cooled to below 0 deg C, it cracks internally. Upon repeated freezing and thawing, the cracks grow, interact, and lead eventually to macroscopic degradation, termed ice damage. This report reviews the phenomenon and considers the underlying mechanisms. New explanations are given for the deleterious effect of deicer salts and for the beneficial effect of entrained air. ... |
|
| Anionic Conducting Oxide Ceramics |
APR 1998 |
10 pages |
| Authors:
Bruce Dunn; John D. Mackenzie; CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This program has emphasized the interrelationships among synthesis, microstructure and properties for oxygen ion conducting ceramics based on copper-substituted bismuth vanadate (Bi V Cu O ), known as BICUVOX. We showed that these materials readily formed dense ceramics with equiaxed microstructures and confirmed that they exhibited high ionic conductivity. Prolonged heat treatments at elevated temperatures did not cause significant changes in conductivity, an important consideration ... |
|
| A Technique for Achieving 4000 Microstrain from Hard PZT |
30 MAR 98 |
9 pages |
| Authors:
Christopher S. Lynch; GEORGIA INST OF TECH ATLANTA SCHOOL OFMECHANICAL ENGINEERING
|
| The year 2 effort was divided between experimental characterization of the constitutive behavior of ferroelectric ceramics and reliability of actuators constructed from these materials. Key results of the study of the constitutive behavior under combined stress and electric field loading were the ability to obtain over 3000 microstrain from PZT without excessive hysteresis or cracking and the characterization of several compositions of PZT under high ... |
|
| Oxygen Ion Conductors Prepared with Nanosize Particles |
23 MAR 98 |
9 pages |
| Authors:
Bruce Dunn; J. D. Mackenzie; CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The instrumentation acquired from this grant consists of two atomic force microscopes (from Park Scientific and Molecular Imaging) and a particle size analyzer (from Micromeritics). The atomic force microscopes are complementary in terms of their operation and use the same controller and software. The Park Scientific instrument has been used to characterize the microstructure development of thin films of the oxygen ion conductor, BICUVOX (Bi(2)V(0.9)Cu(0.1)O(5.35)) over the temperature range from ... |
|
| Ambient Pressure Synthesis of Aerogel-like Vanadium Oxide and MolybdenumOxide |
18 MAR 98 |
12 pages |
| Authors:
John H. Harreld; Winny Dong; Bruce Dunn; CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| An ambient pressure method for drying sol-gel materials has been used to synthesize highly porous vanadium oxide and molybdenum oxide materials with aerogel-like properties. The resulting solids exhibit 80-90% porosity and high surface area (150-280 m2/g). The synthesis approach uses liquid exchange to replace the pore fluid with a low surface tension, nonpolar solvent which reduces the capillary pressures developed during drying. The technique is ... |
|
| U.S.-Japan Research Collaboration on Hard Driving Ceramic Actuators |
18 MAR 98 |
56 pages |
| Authors:
Shoko Yoshikawa; Ming-Jen Pan; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| High field properties of electro-active ceramics are an important issue to understand in order to apply these ceramics in actuator applications. This project was developed to establish research collaborations with Japanese piezoelectric ceramic researchers in order to fully characterize these ceramics. Due to a PI change during the contract, the collaboration was not completed as originally planned. The information exchange was summarized as a trip report. However, at Penn State ... |
|
| First Principles Calculations Using Linear Response Theory for Ferroelectrics |
17 MAR 98 |
4 pages |
| Authors:
Henry Krakauer; COLLEGE OF WILLIAM AND MARY WILLIAMSBURG VA DEPT OF PHYSICS
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| First principles density functional methods using LAPW and LAPW linear response method were applied to study the incipient ferroelectric SrTiO3. Despite similarities to BaTiO3, SrTiO3 remains paraelectric down to zero temperature, transforming instead to an antiferrodistortive structure at 105 K. As a function of wavevector, the linear response calculations show structural instabilities along the R-M-R line in the Brillouin zone, consistent with this antiferrodistortive ground state. Although a ferroelectric type ... |
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Ceramics, Refractories and Glass
