| Investigation of the Compressive Material Properties of PZT and PMN |
01 DEC 1999 |
21 pages |
| Authors:
Lynn M. Ewart; Elizabeth A. McLaughlin; Kim D. Gittings; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
|
 | In U.S. Navy sonar transducers, me electroactive ceramics are subject to mechanical compressive stresses. However, there has been scant research to examine the mechanical effects of compressive loads on electroactive ceramics. The research reported herein measured material properties (compressive strength, Young's modulus, and Poisson's ratio) and studied the behavior in compression and under short circuit conditions of five commercially available lead zirconate titanate (PZT) and lead magnesium ... |
|
| Materials Research Society Symposium Proceedings Volume 600, Electroactive Polymers (EAP) Symposium Held in Boston, Massachusetts on November29-December 1, 1999 |
01 DEC 1999 |
341 pages |
| Authors:
Q. M. Zhang; Takeo Furukawa; Yoseph Bar-Cohen; J. Scheinbeim; MATERIALS RESEARCH SOCIETY WARRENDALE PA
|
| For many years, electroactive ceramic, magnetostrictive material and shape memory alloys have been the primary source of actuation materials for manipulation and mobility systems. Electroactive polymers (EAP) received relatively little attention due to their limited capability. In recent years, effective EAP materials have emerged changing the paradigm of these materials' capability and potential. Their main attractive characteristic is the operation similarity to biological muscles ... |
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| Determination of the Mechanical Properties of Polycrystalline Silicon for MEMS |
DEC 1999 |
7 pages |
| Authors:
George C. Johnson; CALIFORNIA UNIV BERKELEY DEPT OF MECHANICAL ENGINEERING
|
| The research supported under this grant was part of a multi- institution round-robin experiment to determine the elastic modulus and fracture strength of a common material used in microelectromechanical systems (MEMS). Research teams at four institution - Johns Hopkins University, California Institute of Technology, Experiment/Failure Analysis Associates and the University of California, Berkeley - designed unique devices for determining the material properties of interest. All four ... |
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| Investigation of the Mechanics of Windborne Missile Impact on Window Glass |
DEC 1999 |
146 pages |
| Authors:
Scott A. Bole; TEXAS TECH UNIV LUBBOCK DEPT OF CIVIL ENGINEERING
|
| Engineers have recognized that failure of the building envelope is one mechanism that can lead to severe damage of structures during windstorms. The building envelope consists of the roof, doorways, windows, and cladding components that form the exterior wall system of a building. Failure of the building envelope results in internal pressurization of the structure which may lead to structural failure. For this reason, engineers ... |
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| Evaluation of Window Failure Modes |
DEC 1999 |
35 pages |
| Authors:
HUGHES ASSOCIATES INC BALTIMORE MD
|
| A furnace test was conducted to investigate a possible cause of premature failures of one-hour fire-rated window assemblies in a previous test series. In the previous series, two of the four A-30 window assemblies and one of the four A-60 window assemblies failed within eight and ten minutes after the beginning of the test exposure. A suspected cause was damage by welding slag from the attachment ... |
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| Pr3+ -Doped Fluoride Glass for a 589 nm Fibre Laser |
DEC 1999 |
7 pages |
| Authors:
Animesh Jha; LEEDS UNIV (UNITED KINGDOM) DEPT OF MATERIALS
|
| This report results from a contract tasking University of Leeds as follows: The contractor will investigate the development of Pr3+-doped fluoroindate and fluoroaluminate host glasses to determine if the chemistry of their composition can be adjusted so that useful gain at 589 nm can be achieved. 8 glass samples will be delivered to AFRL for evaluation. |
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| An NMR Study of Metallic Glasses |
19 NOV 1999 |
7 pages |
| Authors:
Yue Wu; NORTH CAROLINA UNIV AT CHAPEL HILL
|
| The mechanisms of atomic transport in the supercooled liquid state (SLS) and the nature of glass transition have been challenging problems for decades. It is believed that collective atomic motion plays a key role in the dramatic slow-down of kinetics near the glass transition temperature Tg. Thus, understanding the mechanisms of atomic transport is directly linked to the understanding of the glass forming ability of ... |
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| New Classes of Ceramic Materials for Thermal Barrier Coating Applications |
18 NOV 1999 |
29 pages |
| Authors:
Sankar Sambasivan; NORTHWESTERN UNIV EVANSTON IL
|
| This project investigated the feasibility of using new ceramic materials/concepts for use in thermal barrier coating applications. In one approach, the effect of solid solution on thermal conductivity of refractory spinels (magnesium aluminate-based) was evaluated. Plasma spray process was used to fabricate free-standing discs of spinels with various amounts of cobalt. Preliminary results show that a 2% doping of cobalt in MgA12O4 was effective in ... |
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| US-Japan Seminar (9th) on Dielectric and Piezoelectric Ceramics Held in Okinawa, Japan on 2-4 Nov 99. Program Summary and Extended Abstract |
05 NOV 1999 |
|
| Authors:
Tadashi Takenaka; SCIENCE UNIV OF TOKYO (JAPAN)
|
 | Proceedings from the 9th U.S.-Japan Seminar on Dielectric & Piezoelectric Ceramics, held 2-4 Nov 99, in Okinawa, Japan, includes contributed papers pertaining to: (1) Basic Science; (2) Piezoelectric Materials and Devices; (3) Thin Film Dielectrics: (4) Multilayer Ceramic Capacitors; and (5) Advanced Processing and Packaging. |
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| The Ninth U.S. - Japan Seminar on Dielectric and Piezoelectric Ceramics.Program and Evaluations |
05 NOV 1999 |
50 pages |
| Authors:
Thomas R. Shrout; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| The Ninth U.S.-Japan Seminar on Dielectric and Piezoelectric Ceramics was held on Okinawa, Japan, through November 2-5, 1999. The local organization was from the Science University of Tokyo and the Tokyo Institute of Technology. The total number of papers was 106: 69 Japanese and 37 U.S.; 40% of the papers were from industry. The principal technical topics were: (1) Piezoelectric Ceramics (bulk), (2) Multilayer Capacitors, and ... |
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| Nanochannel Glass Replica Membranes |
02 NOV 1999 |
|
| Authors:
Douglas H. Pearson; Ronald J. Tonucci; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| The present invention is a process for making a nanochannel glass (NCG) replica, having the steps of: coating a face of an etched NCG with a replica material (with or without an intervening buffer layer), where the etched NCG face has a plurality of channels arranged in a desired pattern, to form a replica coating on the NCG conforming to the pattern; and removing the replica coating from the etched ... |
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| Microscale Plasticity and Fracture Toughness of Ti3SiC2 at Ambient and High Temperatures |
NOV 1999 |
32 pages |
| Authors:
M. W. Barsoum; DREXEL UNIV PHILADELPHIA PA DEPT OF MATERIALS ENGINEERING
|
| The goal of this work was to develop a science-based understanding of the structure property relationships in Ti3SiC2. Late in 1995 we synthesized for the first time dense, bulk single phase samples of Ti3SiC2. Preliminary characterization has shown it to be a ternary compound with a unique set of properties, machinability similar to that of graphite, excellent oxidation resistance, relatively low density 4.5 gm/cu cm and non-susceptibility ... |
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| Structure Property Relationships in Ti3SiC2 |
NOV 1999 |
23 pages |
| Authors:
M. W. Barwoum; L. Farber; I. Levin; DREXEL UNIV PHILADELPHIA PA DEPT OF MATERIALS ENGINEERING
|
| The dislocation structure of a typical low angle boundary associated with a kink band in a sample of Ti3SiC2 deformed at room temperature was studied by HRTEM. The boundary had both tilt and twist components. To account for both, the boundary was interpreted to be composed of parallel, alternating, mixed perfect dislocations with two different Burger's vectors lying in the basal plane at an angle of ... |
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| Concrete Floor Condition Assessment |
NOV 1999 |
12 pages |
| Authors:
C. D. Gaughen; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
|
| The Users Guide presents a systematic approach to assessing the condition of concrete floors prior to specifying one of three coating systems: (A) Thin film coating system (>/= 13 mils: 1 mil = 0.001"), (B) Thick film coating system (>/= 250 mils), and (C) Overcoating sound coating systems. By assessing the condition of floor surfaces, coating failures resulting from the following practices should decrease: (1) ... |
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| Ultra-Fast Portable Metallic/Concrete Plate Cutting |
28 OCT 1999 |
114 pages |
| Authors:
Vladimir Hlavacek; CERAMIC AND MATERIALS PROCESSING INC CLARENCE NY
|
| The goal of this report is to develop and evaluate methods of ultra- high and high-rate cutting technologies for use in military and civilian realm. The information presented in this report reveals that defeating exposed rebars, steel reinforced concrete walls, steel encased concrete doors, and steel plate doors is within reach of current technologies. We did not analyze any exotic solutions but proposed to use ... |
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| Fundamental Studies of Novel Contact-Damage Resistant Ceramics |
30 SEP 1999 |
8 pages |
| Authors:
Nitin P. Padture; CONNECTICUT UNIV STORRS
|
| The objective of the program is to elucidate novel concepts (including microstructures, processes, and materials) in the following 2 key areas of ceramics applications relevant at the U.S. Air Force: (1) contact- damage resistance and (2) thermal insulation/protection. During the period covered by this report, major innovations in the above 2 areas have been achieved and are summarized. |
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| Durability of Fiber-Reinforced Concrete Under Flexural Stress in a Severe Marine Environment |
SEP 1999 |
214 pages |
| Authors:
Edward F. O'Neil; Jack T. Devlin; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS STRUCTURES LAB
|
| In July 1975, the U.S. Army Engineer Research and Development Center (ERDC), initiated a long-term durability study of fiber-reinforced concrete exposed to a severe marine environment. Fifty concrete beams were constructed that were reinforced with various types and sizes of distributed fibers available on the market at the time (carbon-steel, stainless steel, and glass). The beams were then placed at midtide elevation on the exposure wharf at the ERDC Severe ... |
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| Development of a Constitutive Model for Numerical Simulation of Projectile Penetration into Brittle Geomaterials |
SEP 1999 |
227 pages |
| Authors:
J. D. Cargile; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENGINEER RESEARCH AND DEVELOPMENT CENTER
|
| A nonlinear, inelastic fracture model for brittle geomaterials has been developed for simulating the response of these materials to high-velocity projectile penetration. Laboratory mechanical property experiments show a transition in the shearing response for these materials from brittle at low pressures to ductile at high pressures. The model has the underlying assumption that the shearing response can be resolved into a brittle cohesive component and ... |
|
| International Workshop on Applied Aspects of Interface Science (AAIS) |
SEP 1999 |
75 pages |
| Authors:
RUSSIAN ACADEMY OF SCIENCES ST PETERSBURG INST OF PROBLEMS OF MECHANICAL ENGINEERING
|
| This volume is a collection of selected original papers presented at the International Workshop on Applied Aspects of Interfaces Science held at the Palace of Scientists, St. Petersburg, Russia, September 22-24, 1999. The workshop objective was to present current research on advanced nanostructured materials and high temperature superconducting materials characterized by nano- scaled coherence length. Focus was placed synthesis and processing, modeling, characterization and properties, and applications. A total of ... |
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| Heat Treatment Effects on Microstructure of SiC Fiber Preforms |
JUL 1999 |
16 pages |
| Authors:
Ramakrishna T. Bhatt; Yuan L. Chen; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Preforms of BN/SiC coated Sylramic SiC fibers were heat treated at 1420 deg, 1600 deg, and 1800 deg C in 0.1 MPa argon or at 1800 deg C in 103 MPa nitrogen for 1 h. Optical, SEM, and TEM techniques were used to analyze the effects of environmental exposure on constituent microstructure of the preforms. TEM analysis of the as-received preforms indicates that the CVI BN coating is predominantly amorphous ... |
|
| Demonstration and Validation of Thermal Spray Vitrification of Lead- Containing Paint on Steel Structures |
JUL 1999 |
86 pages |
| Authors:
Robert A. Weber; Jeffrey Boy; Roy Zatorski; Ashok Kumar; CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPAIGN IL
|
| In the past, red lead primer was used to control corrosion on many common steel structures maintained by the Department of Defense (DoD). Thermal spray vitrification (TSV) technology has been demonstrated as a way to remove lead-based paint coatings from steel substrates that are not suitable for overcoating. In the TSV process, lead-based paints are thermally sprayed with a specially-formulated powdered glass feedstock that absorbs and encapsulates lead. When the ... |
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| Dynamic Behavior of Brittle Materials |
JUL 1999 |
8 pages |
| Authors:
L. B. Freund; BROWN UNIV PROVIDENCE RI
|
| The goal of the program was to characterize and quantify physical processes involved in failure of brittle materials under impact loading conditions, and to synthesize results to identify properties which determine the effectiveness of a system (material and configuration) in resisting failure. This was accomplished by developing new methodologies which integrate concepts in mechanics and materials science. Among the accomplishments are: determining the pressure-shear response of alumina powders and of ... |
|
| Behavior of Materials in a Dynamic Environment: Summary of Phase II results |
JUL 1999 |
235 pages |
| Authors:
M. El-Raheb; K. Weber; V. Hohler; DOW CHEMICAL CO MIDLAND MI
|
| A theoretical and experimental study was conducted on stress waves and ballistic performance of weakly coupled stacks of AlN tiles bonded by thin polyurethane films. The cylindrical projectile was made of tungsten alloy with L/D = 6 weighing 61g at a velocity close to 1170 m/s striking the stack centrally. Total thickness of the stack ranged between 3" and 1.5", and with individual tile thicknesses ... |
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| Channeled Ceramic Structure and Process for Making Same |
29 JUN 1999 |
|
| Authors:
Todd Jessen; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Ceramic structure having porosity of 10-80% is characterized by a solid ceramic matrix having therein elongated and parallel channels, the structure is made by a process that includes the steps of: (a) arranging tows of elongated fibers parallel to each other to form a fiber preform, (b) contacting the fiber preform with a matrix precursor whereby the matrix precursor deposits around the fibers, (c) removing the fiber preform from the ... |
|
| Test Excavations at 20 Archeological Sites on the Poinsett Electronic Combat Range, Sumter County, South Carolina, Volume 2: Appendices |
JUN 1999 |
254 pages |
| Authors:
John S. Cable; Maynard B. Cliff; Gary A. Hebler; GEO-MARINE INC PLANO TX
|
| This appendix presents the descriptive results of the ceramic analysis for the 1997 Phase II investigations at 20 prehistoric archeological Sites located in Poinsett Electronic Combat Range, Shaw Air Force Base, Sumter, South Carolina. The collection of 2,622 ceramics represents a sampling of nearly every prehistoric occupational period present in the Lower Wateree River valley, an estimated span of some 3,000 to 3,500 years. The typological classification and functional characteristics ... |
|
| Mixing and Transporting Concrete |
24 MAY 1999 |
23 pages |
| Authors:
Greg Vinci; DEPARTMENT OF DEFENSE WASHINGTON DC
|
| The successful placement of concrete is dependent upon careful mixing, the proper equipment, and adequate transportation. This paper will define, analyze and demonstrate the importance of each in the overall process of placing concrete. |
|
| The Role of Microstructural Damage in the Thermal Diffusivity of Fiber- Reinforced Ceramic-Matrix Composites |
14 MAY 1999 |
105 pages |
| Authors:
Frank W. Zok; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| A phase-sensitive photothermal technique for the determination of the thermal diffusivity of solids and the thermal, conductance of cracks and interfaces has been developed. The technique has been validated using a model systems comprising stainless steel disks, placed either in direct contact with each other or with thin polyethylene sheets between them. The corresponding heat flow analysis has also been developed. The technique has been used to study in detail ... |
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| Multi-Cylinder Apparatus for Making Optical Fibers, Process and Product |
04 MAY 1999 |
|
| Authors:
Reza Mossadegh; Jasbinder Sanghera; Ishwar Aggarwal; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A vertically disposed apparatus used to make core-clad optical fibers includes an inner elongated cylinder removably closed at the top and provided at the bottom with an inner exit port of a smaller diameter than the inner cylinder and an outer cylinder, disposed around the inner cylinder removably closed at the top and provided at the bottom with an outer exit port of a smaller diameter than the outer cylinder. ... |
|
| The Detection of Doped Cr Presence in Sr(0.6)Ba(0.4)Nb2O3 by SIMS |
MAY 1999 |
12 pages |
| Authors:
Unchul Lee; ARMY RESEARCH LAB ADELPHI MD
|
| Photorefractive materials like SrBaNb (SBN) have optical properties that can have several military applications. To improve the figures of merit for these materials, it is very important to have better control of Cr dopant in the SBN. Since the amount of Cr dopant is so small, the usual analytical techniques are not adequate to analyze this material. In this report, the incorporation of Cr into SBN using secondary ion mass ... |
|
| Microstructural Design of Tough Ceramics for Contact Damage Resistance |
MAY 1999 |
86 pages |
| Authors:
Helen M. Chan; Brian R. Lawn; LEHIGH UNIV BETHLEHEM PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The results of research investigating contact damage and fatigue of ceramics is described, with particular attention to microstructural design. The aims were as follows: (1) To develop experimental testing methodologies, using Hertzian contacts, for studying the fundamental short-crack damage properties of tough ceramics, notably in silicon carbide and silicon nitride; (2) To examine the role of critical microstructural variables (grain size and shape, grain boundary phase, interface energy, internal stress) ... |
|
| The US-Japan Seminar (8th) on Dielectric and Piezoelectric Ceramics Held in Plymouth, Massachusetts on October 15-18, 1997; Program Summary and Extended Abstracts |
01 APR 1999 |
|
| Authors:
Thomas R. Shrout; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
|
| A Novel Manufacturing Processing Route for Forming High-Density Ceramic Armor Materials: Phase I - SBIR |
APR 1999 |
48 pages |
| Authors:
Ramas V. Raman; CERACON INC SACRAMENTO CA
|
| The objective of the Phase I small business innovative research (SBIR) project was to demonstrate the feasibility of applying the Combustion Synthesis (CS)/Ceracon Consolidation Process for forming 10-cm-diameter, 2.5-cm- thick high-density titanium carbide (TiC) and titanium diboride (TiB2) pieces. The Phase I project demonstrated for the first time the feasibility of CS initiation to form TiC and TiB2 by using Ceracon's hot, granular media and their in-situ consolidation. The effects ... |
|
| A Novel Manufacturing Processing Route for Forming High-Density Ceramic Armor Materials: Phase II- SBIR |
APR 1999 |
104 pages |
| Authors:
Rams V. Raman; CERACON INC SACRAMENTO CA
|
| The feasibility of a combustion synthesis/Ceracon forging (CS/CF) fabrication process for low-cost high-quality ceramic armor is demonstrated. CS of titanium (Ti) and carbon (C) forming titanium carbide (TiC) was followed by a quasi-isostatic pressurization and densification to produce tiles with 95% + densities with sizes of up to 15 cm x 15 cm x 2.5 Cm. Several tiles were fabricated and delivered to the U.S. Army Research Laboratory (ARL) for ... |
|
| Self-Propagating High-Temperature Synthesis and Dynamic Compaction of Titanium Boride and Titanium Carbide |
APR 1999 |
51 pages |
| Authors:
Liya Wang; Levi T. Thompson; T/J TECHNOLOGIES INC ANN ARBOR MI
|
| Titanium carbide (TiC) and titanium diboride (TiB2) ceramic disks, with diameters of 100 mm and thicknesses of 25 mm, were fabricated with densities above 95% and 98% of theoretical, respectively, using a self- propagating high-temperature synthesis/dynamic consolidation (SHS/DC) process. First, an SHS reaction was initiated in a green body made from precursor powders. Second, after the completion of the SHS reaction, the freshly synthesized ceramic product was densified to near-full ... |
|
| Upscaled Self-Propagating High-Temperature Synthesis (SHS)/Dynamic Compaction Processing |
APR 1999 |
59 pages |
| Authors:
R. M. Cooper; XFORM INC COHOES NY
|
| Titanium carbide (TiC) and titanium diboride (TiB2 ceramics were formed from elemental powders using a Gleeble 1500 dynamic thermomechanical process simulator. In the first step of a two-step process, a self-propagating high-temperature synthesis (SHS) reaction was initiated by the passage of an electric current through the powdered green body. The temperature of the body was maintained at about 800 deg C, and the reaction rate was controlled by the application ... |
|
| Ceramic Coated Piston Rods for Civil Works |
APR 1999 |
48 pages |
| Authors:
Robert A. Weber; Raymond Zatorski; CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPAIGN IL ENGINEERING AND MATERIALS DIV
|
| The U.S. Army Corps of Engineers uses many hydraulic pistons on its Civil Works structures. Recent failures of ceramic coated piston rods in the Jacksonville District indicate that specifications for these rods need to be updated and enhanced. This report discusses results of tests performed on carbon steel rods with varying bond coats applied with one of several methods. Top coats were also varied, and sealers were used only on ... |
|
| Advanced Piezomaterials for Transducer Applications |
APR 1999 |
6 pages |
| Authors:
Brian Pazol; MATERIALS SYSTEMS INC LITTLETON MA
|
| Task 1: High Volume Fraction 1-3 Composite. A semiautomatic ejection mechanism was designed and will be retrofitted into an existing MSI tool body. Semiautomatic ejection will minimize part distortion due to manual handling, decrease process time, and increase yields. Task 2: High Displacement Piezoceramic. More than fifty formulations of PLZT have been batched and tested to optimize the composition for the highest dielectric and piezoelectric properties with a target Curie ... |
|
| Nanostrutured Ceramic Nitride Powders and a Method of Making the Same |
02 MAR 1999 |
|
| Authors:
Lynn K. Kurihara; Gan Moog Chow; Paul E. Schoen; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Near net-shapeable nanostructured ceramic nitride powder and a process for producing the same by nitriding molecular precursor powder in a nitrogen containing atmosphere, e.g., in ammonia, to form nanostructured ceramic nitride powder. |
|
| Evaluation and Characterization of Ceramic Bearing Materials |
MAR 1999 |
40 pages |
| Authors:
Paul J. Huang; Clifford W. Hubbard; Gary A. Gilde; Jeffrey J. Swab; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This report discusses the findings from one phase of our ongoing work to evaluate materials for Army bearing systems. The objective of this phase is to determine the response and longevity of various silicon nitride Si3N4 materials to rolling contact fatigue (RCF) using hybrid and all-ceramic systems. Tests were conducted under regular lubrication and lubrication-starved conditions for extended periods. A correlation between RCF life and the ... |
|
| Fracture and Fatigue Crack Growth Behavior of Advanced Ceramic Matrix Composites |
MAR 1999 |
6 pages |
| Authors:
Dennis J. Buchanan; DAYTON UNIV OH
|
| Ultrasonic C-scans have successfully been used to investigate damage from notches and holes in Nexte1610 /Aluminosilicate (N610/AS) during tensile and fatigue loading conditions. Sectioned fatigue specimens verified that the region of distributed matrix damage and longitudinal fiber breakage correlated well with the C-scan damage zone at 23C. At 950C the C-scan data showed that the damage zone was confined to the notch plane where damage was primarily due to self ... |
|
| Performance Criteria for Concrete Repair Materials, Phase II Summary Report |
MAR 1999 |
74 pages |
| Authors:
James E. McDonald; Alexander M. Vaysburd; Peter H. Emmons; Randall W. Poston; Keith E. Kesner; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
|
| The results of a study to develop performance criteria for cement- based repair materials are summarized herein. Results of laboratory tests and field performance studies were correlated and guidance for selection of repair materials that would reduce the risk of premature failures was developed. This guidance includes a standard protocol for repair material data sheets and proposed performance criteria. Results of this study illustrate the significant effect of drying shrinkage ... |
|
| A Feasibility Study of Liquid Phase Sinter Forming of a Model Ceramic System |
MAR 1999 |
85 pages |
| Authors:
Roland C. Roeder; 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. Tests to determine the ability ... |
|
| Review of Developments in Fracture and Fatigue of Ceramic Matrix Composites |
MAR 1999 |
70 pages |
| Authors:
Victor Birman; Larry Byrd; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| A review of recent developments and state of the art in damage, fatigue and particularly, high-temperature fatigue of ceramic matrix composites is presented. Both laminated, as well as woven configurations are considered, while whisker and particle-reinforced materials are not covered in this review. Based on a detailed discussion of the mechanisms of failure, the problems that have to be addressed for a successful implementation of ceramic matrix composites in design ... |
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| Siloxane Unsaturated Hydrocarbon Based Polymers |
23 FEB 1999 |
|
| Authors:
Teddy M. Keller; David Y. Son; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| This invention relates to a new class of novel linear inorgantc-organic hybrid polymers of varying molecular weight that are useful for making high temperature oxida- tively stable thermosets, and these novel linear polymers arc in themselves oxidatively stable at high temperatures between 600 deg-1000 deg C. These new materials have repeat units that contain at least one alkynyl group and at least one siloxanyl group within the backbone of these ... |
|
| Making Aggregates and Articles Made Therefrom |
23 FEB 1999 |
|
| Authors:
Manfred Kahn; Mark Chase; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| The process for making a porous mass containing dense aggregates or granules includes the steps of mixing powder with more than 10% by weight of a binder to form agglomerated powder, heating the agglomerated powder to remove the binder and to grow crystallites in the powder to an average diameter exceeding 5 microns to form a porous mass containing the dense aggregates, and cooling the porous mass. The porous mass ... |
|
| Ceramic Structure with Backfilled Channels |
02 FEB 1999 |
|
| Authors:
Todd Jessen; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Ceramic structure and process for its preparation wherein the structure is composed of a matrix having therein parallel and spaced reinforcing fibers and strands of backfilled ceramic material, the strands being parallel to the reinforcing fibers; and wherein the process includes the steps of arranging tows of fugitive and reinforcing fibers parallel to each other to form a fiber preform, contacting the preform with a matrix precursor whereby the precursor ... |
|
| Single-Crystal Material on Non-Single-Crystalline Substrate |
01 FEB 1999 |
25 pages |
| Authors:
Karl D. Hobart; Francis J. Kub; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A method for making a multilayered structure with a single crystal film bonded to a polycrystalline substrate has the steps of bonding a single crystal film to a polycrystalline substrate; and growing an epitaxial layer on said single crystal film bonded to said polycrystalline substrate. |
|
| Experimental and Numerical Investigations on Failure Mechanisms in Fiber-Reinforced Ceramics |
29 JAN 1999 |
51 pages |
| Authors:
H. L. Schreyer; M. L. Wang; NEW MEXICO UNIV ALBUQUERQUE DEPT OF MECHANICAL ENGINEERING
|
| The primary focus on this research was to model the evolution of microcracks at the interfaces of grains and inclusions in quasibrittle materials. Several unique aspects have been developed as part of the research. These include the application of the material point method to a new class of problems and the formulation of a thermodynamically-based decohesion constitutive equation. In addition, numerical algorithms were formulated to ... |
|
| Silicon Nitride Hybrid Bearing Fatigue Life Comparisons |
15 JAN 1999 |
23 pages |
| Authors:
E. Y. Robinson; AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS
|
| Research to improve high-speed ball bearings for spacecraft applications has led to development of ceramic materials for bearing components, and the need to acquire sufficient fatigue life data to show the merits of various ceramic materials and fabrication processes, in comparison with the vast amount of steel bearing fatigue data acquired over many decades. In order to eliminate bias from such evaluations it is best to conduct ... |
|
| Influence of Loading Frequency on the Elevated Temperature Fatigue Behavior of Fiber-Reinforced Ceramic Composites |
15 JAN 1999 |
33 pages |
| Authors:
John W. Holmes; MICHIGAN UNIV ANN ARBOR CERAMIC COMPOSITES RESEARCH LAB
|
| Cyclic tension-tension experiments were conducted on a ceramic matrix composite of continuous Nicalon SiC-fibers in a calcium-aluminosilicate matrix. Two different stress ratios (R = sigma(min)/sigma(max)) were studied (R = 0.5 and R = 0.05) at a loading frequency of 200 Hz. Specimens tested at R = 0.05 were found to have a shorter fatigue life than specimens tested at R = 0.5. The fatigue limit (defined ... |
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Ceramics, Refractories and Glass
