| Ultra High Temperature Ceramics for Aeropropulsion and Aerospace Use |
07 Oct 2008 |
21 pages |
| Authors:
Julian M Fernandez; SEVILLE UNIV (SPAIN) DEPT DE FISICA DE LA MATERIA CONDENSADA
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 | This report results from a contract tasking University of Seville as follows: The poor oxidation resistance of UHTCs is the predominant factor limiting their applicability to aerospace applications. The purpose of this study is to perform an extensive research of these materials under conditions representative of propulsion environments, that will lead to an understanding of process that will improve these materials performance. The initial materials to be studied will be ... |
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| Evaluation of Minimum Asphalt Concrete Thickness Criteria |
Oct-2008 |
112 pages |
| Authors:
Haley P Bell; L W Mason; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| Personnel of the U.S. Army Engineer Research and Development Center (ERDC) were tasked by Headquarters, Air Combat Command, to evaluate the Department of Defense's (DoD) minimum asphalt concrete thickness criteria outlined in United Facilities Criteria 3-260-02. Recent improvements to the DoD's flexible pavement design procedure and a renewed emphasis on the design and construction of contingency pavements had prompted concerns regarding the design and evaluation of thin asphalt concrete pavements. ... |
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| Biaxially Textured YBa2Cu3O7-x Films Deposited on Polycrystalline Flexible Yttria-Stablized Zirconia Ceramic Substrates |
Oct 2008 |
10 pages |
| Authors:
C V Varanasi; J Burke; R Lu; J Wu; L Brunke; L Chuck; H E Smith; I Maartense; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Biaxially textured YBa2Cu3O7-x (YBCO) films were grown on polycrystalline flexible yttria-stabilized zirconia (YSZ) ceramic substrates (Ceraflex) buffered with MgO and LaMnO3 layers. These substrates were initially coated with silica glass to obtain a smooth surface and then biaxially textured MgO buffer layers were deposited by ion beam assisted deposition (IBAD-MgO). Lanthanum manganate (LMO) cap layers and YBCO layers were then deposited by the pulsed laser ablation method. Highly textured YBCO ... |
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| Experimental and Theoretical Investigation of the High-Pressure Behavior of Concrete |
01-Sep-2008 |
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| Authors:
Oana Cazacu; Martin J Schmidt; Mark L Green; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
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 | The results of an experimental study aimed at characterizing the behavior of concrete for high confining pressures (up to 500MPa) are reported. The main characteristics of the response under deviatoric conditions are quasi-linearity in the elastic regime, stress-path dependency, and gradual change from compressibility to dilatancy under increasing deviatoric stress. By performing the cyclic triaxial compression tests with several load-creep-unload and reload cycles, the time influence on the overall behavior ... |
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| Toward Modeling Limited Plasticity in Ceramic Materials |
01-Sep-2008 |
22 pages |
| Authors:
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The characteristic features of many armor-related ceramic materials are the anisotropy on the micro-scale level and the very limited, though non-vanishing, plasticity due to limited number of the planes for plastic slip. This work in progress is targeted toward revising phenomenological models of such materials with limited number of slip planes. In order to emphasize the key ideas of our approach, we illustrate the approach using the simplest possible model, ... |
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| Effects of Temperature and Steam Environment on Fatigue Behavior of Three SIC/SIC Ceramic Matrix Composites |
01-Sep-2008 |
229 pages |
| Authors:
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The fatigue behavior of two woven SiC-SiNC ceramic matrix composites (CMCs) was investigated at 1300 deg C in laboratory air and in steam. The first composite (C1) consists of a PIP SiNC matrix reinforced with Sylramic (Syl) fibers woven in a five-harness satin weave fabric and coated with a proprietary dual-layer interface. The second composite (C2) consists of a modified PIP SiNC matrix reinforced with Sylramic-iBN (Syl-iBN) fibers woven in ... |
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| Creep Behavior of Oxide/Oxide Composites with Monazite Fiber Coating at 1100 deg C in Air and in Steam Environments |
01-Sep-2008 |
425 pages |
| Authors:
Tufan Yeleser; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| The creep behavior of six oxide-oxide ceramic-matrix composites (CMCs) was investigated at 1100C in air and in steam. The six CMC systems had an alumina matrix reinforced with Nextel (TradeMark)610 fibers. The CMC systems C1, C2 and C3 were reinforced with 10 uni-directional fiber layers in a symmetric cross-ply orientation while C4, C5,and C6 were reinforced with 8 plies of fiber fabric woven. Composites C2, C3, C4, and C6 had ... |
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| Silicon Carbide Technologies for Lightweighted Aerospace Mirrors |
Sep 2008 |
10 pages |
| Authors:
Lawrence E Matson; Ming Y Chen; Brett DeBlonk; Iwona A Palusinski; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH
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| The use of monolithic glass and beryllium to produce lightweighted aerospace mirror systems has reached its limits due to the long lead times, high processing costs, environmental effects and launch load/weight requirements. New material solutions and manufacturing processes are required to meet DoD's directed energy weapons, reconnaissance/surveillance, and secured communications needs. Over the past several years the Air Force, MDA, and NASA has focused their efforts on the fabrication, lightweighting, ... |
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| Rare Earth Aluminophosphosilicate Glass Precursors for Ceramic-Matrix-Composites (REAPS CMC's) |
11 Jul 2008 |
24 pages |
| Authors:
William T Petuskey; ARIZONA STATE UNIV TEMPE
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| This project was dedicated to assessing the utility of rare earth aluminophosphosilicate (REAPS) glasses within the Al203-AlP04-LaP04-Si02 system as precursors for fabricating ceramic-matrixcomposites of (Al6Si2013) and monazite (LaP04). The specific objective was to investigate selected issues for devising strategies of low-temperature pathways of viscous sintering of glass powders and crystallization anneals to produce dense monolithic ceramics of very fine textures. The ultimate goal, beyond the scope of this work, will ... |
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| Microstructural Effects on the Corrosion Behavior of Alloys and Ceramics |
30-Jun-2008 |
45 pages |
| Authors:
Todd Allen; Lizhen Tan; NATIONAL ASSOCIATION OF CORROSION ENGINEERS HOUSTON TX
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| The objective of this research was to investigate the effect of microstructure on the corrosion behavior of metals and ceramics. Representative materials from the important engineering alloys and ceramics were studied to determine their corrosion behavior in supercritical water and during cyclic oxidation in air. The materials included Incoloy alloy 800H, Inconel alloy 617, 12%Cr ferritic-martensitic steel HCM12A, and silicon carbide fabricated by means of chemical vapor deposition (CVD). The ... |
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| Interface Defeat for Unconfined SiC Ceramics |
17 Jun 2008 |
10 pages |
| Authors:
Thilo Behner; Anderson; Charles E Jr; Timothy J Holmquist; Matthias Wickert; Douglas W Templeton; ARMY TANK-AUTOMOTIVE AND ARMAMENTS COMMAND WARREN MI
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| Experiments were performed to determine the dwell-penetration transition velocity for an unconfined SiC target impacting a long gold rod. Some of the targets used a small copper buffer to attenuate the initial impact shock which increased the transition velocity significantly (by a factor of approximately 2). Transition velocity for bare SiC is approximately 800 m/s whereas the buffered targets had a transition velocity of approximately 1550 m/s. Once penetration is ... |
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| Origin of Ultralow Friction and Wear in Ultrananocrystalline Diamond |
11 Jun 2008 |
7 pages |
| Authors:
Andrew R Konicek; D S Grierson; P U Gilbert; W G Sawyer; A V Sumant; Robert W Carpick; PENNSYLVANIA UNIV PHILADELPHIA DEPT OF PHYSICS AND ASTRONOMY
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| The impressively low friction and wear of diamond in humid environments is debated to originate from either the stability of the passivated diamond surface or sliding-induced graphitization/rehybridization of carbon. We find ultralow friction and wear for ultrananocrystalline diamond surfaces even in dry environments, and observe negligible rehybridization except for a modest, submonolayer amount under the most severe conditions (high load, low humidity). This supports the passivation hypothesis, and establishes a ... |
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| Study of Fundamental Photoelectric Properties Related to Formation of Holographic Gratings in Photorefractive Materials |
May 2008 |
6 pages |
| Authors:
A A Kaplyanski; RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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| This report results from a contract tasking A.F. Ioffe Physical-Technical Institute as follows: The contractor will investigate the relations between photoelectric and electric properties of several doped noncentrosymmetric crystals, mainly of iron doped lithium niobate crystals, LiNbO3:Fe, and their photorefractive properties. Photovoltaic effect, photo- and dark conductivity will be studied experimentally in parallel with studies of formation and other properties of holographic gratings in the samples of LiNbO3:Fe, which differ ... |
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| Adaptive Control of Freeze-Form Extrusion Fabrication Processes (Preprint) |
May 2008 |
41 pages |
| Authors:
Xiyue Zhao; Robert G Landers; Ming C Leu; MISSOURI UNIV-ROLLA DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing process that extrudes high solids loading aqueous ceramic pastes in a layer-by-layer fashion below the paste freezing temperature for component fabrication. Due to effects such as the air bubble release, agglomerate breakdown, change in paste properties during extrusion as a result of liquid phase migration, etc., the extrusion force is difficult to control. In this paper, an adaptive controller is proposed to ... |
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| Plastic Flow and Failure Resistance of Metallic Glass: Insight from In Situ Compression of Nanopillars |
14 Apr 2008 |
8 pages |
| Authors:
Z W Shan; Ju Li; Y Q Cheng; A M Minor; S A Asif; C L Warren; E Ma; PENNSYLVANIA UNIV PHILADELPHIA DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| We report in situ nanocompression tests of Cu-Zr-Al metallic glass MG pillars in a transmission electron microscope. This technique is capable of spatially and temporally resolving the plastic flow in MGs. The observations reveal the intrinsic ability of fully glassy MGs to sustain large plastic strains, which would otherwise be preempted by catastrophic instability in macroscopic samples and conventional tests. The high ductility in volume-limited MGs and the sample size ... |
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| Sintering Ceramic Laser Materials with a High Power 83 GHz Beam |
Apr 2008 |
3 pages |
| Authors:
Arne W Fliflet; Melissa Hornstein; Steven H Gold; Manfred Kahn; M A Imam; NAVAL RESEARCH LAB WASHINGTON DC MATERIAL SCIENCE AND TECHNOLOGY DIV
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| Millimeter-wave processing (sintering) of ceramic laser host materials has been under investigation at the Naval Research Laboratory (NRL) for high energy laser (HEL) applications. Advantages of polycrystalline, compared to single-crystal laser host materials, include lower processing temperature, higher gain from higher dopant concentrations, cheaper fabrication, and larger devices. Millimeter-wave processing has been shown to be an effective alternative to conventional vacuum furnaces for pressure-free sintering of low-loss oxide ceramic materials. ... |
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| Correlation Between Thermodynamic and Kinetic Fragilities in Non-Polymeric Glass-Forming Liquids (Preprint) |
Feb 2008 |
10 pages |
| Authors:
Oleg N Senkov; Daniel B Miracle; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| A theoretical relationship between reduced excess heat capacity of super-cooled liquid at the glass transition temperature, fragility index m and reduced glass transition temperature, was derived from fragile non-polymeric glass-forming liquids under the assumptions that the fragile behavior of these liquids is described by the Vogel-Fulcher-Tammann (VFT) equation, the excess heat capacity of liquid is a hyperbolic function of the absolute temperature, and the VFT temperature is equal to the ... |
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| SiC Armor Tiles via Magnetic Compaction and Pressureless Sintering |
27-Jan-2008 |
21 pages |
| Authors:
Bhanu Chelluri; Ed A Knoth; L P Franks; IAP RESEARCH INC DAYTON OH
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| The purpose of the SBIR, entitled "Continuous Dynamic Processing of Ceramic Tiles for Ground Vehicle Protection", was to create a high rate, cost effective manufacturing method for producing silicon carbide (SiC) tiles via a combination of high density Dynamic Magnetic Compaction (DMC) for near net shape green body forming and Pressure-less Sintering (PS) for full density sintered body. |
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| Thermocouple Interactions During Testing of Melt Infiltrated Ceramic Matrix Composites (Postprint) |
Jan-2008 |
12 pages |
| Authors:
R John; G Ojard; G Morscher; Y Gowayed; U Santhosh; J Ahmad; R Miller; PRATT AND WHITNEY AIRCRAFT GROUP EAST HARTFORD CT
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| As high performance ceramic matrix composite systems, such as Melt Infiltrated (MI) SiC/SiC, are being considered for advanced gas turbine engine applications, the characterization of the material becomes more important. A series of test were conducted where Pt and Ni sheathed Pt thermocouples were used to monitor temperature for short and long duration fast fracture, fatigue and creep tests. While it is known that Si forms eutectics with Pt and ... |
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| Single Crystal Diamond Nanomechanical Dome Resonator |
Jan 2008 |
3 pages |
| Authors:
M K Zalalutdinov; J W Baldwin; B B Pate; J Yang; J E Butler; B H Houston; NAVAL RESEARCH LAB WASHINGTON DC ACOUSTICS DIV
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| Superior mechanical and optical properties of single crystal (SC) diamond in combination with a chemically inert and bio-compatible surface enable the design and fabrication of novel nanoscale devices for sensing and signal processing applications. In this letter, we present the first fabrication and operation of high-frequency nanomechanical resonators implemented in 100-nm-thick SC diamond films epitaxially grown on SC synthetic diamond. The method of fabrication is based on introducing a pattern ... |
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| Functional Ceramic Ferroelectromagnetic Materials in Single Phase Solid-Solutions |
05 DEC 2007 |
22 pages |
| Authors:
Ratnamala Chatterjee; INDIAN INST OF TECH NEW DELHI CENTRE FOR MATERIALS SCIENCE AND TECHNOLOGY
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| 1. Perform a detailed study on magneto-dielectric effect in the ferroelectric ferromagnet (FEM) ternary oxide solid solutions like Bi(TM)O3-(La1-xREx)0.67(Ba/Ca)0.33MnO3-BTiO3,where TM=transition metal, initially Fe, RE=Rare Earth and B= Ba, Pb. 2. To find suitable composition such that the ferroelectric and ferromagnetic properties are observable at or near room temperature. 3. To decrease the difference between the ferroelectric (Tfe) and ferromagnetic (TN or Tc) transition temperatures by modifying BiFeO3, and 4. To ... |
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| Dynamic Response and Simulations of Nanoparticle-Enhanced Composites |
15 NOV 2007 |
246 pages |
| Authors:
P. R. Mantena; Ahmed Al-Ostaz; Alexander H. Cheng; MISSISSIPPI UNIV UNIVERSITY MS COMPOSITE STRUCTURES AND NANO ENGINEERING RESEARCH GROUP
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| Objectives of this research are to characterize the: (a) vibration and acoustic response; (b) low-velocity impact and high-strain energy absorption; (c) effects of freeze-thaw cycling; and (d) molecular dynamics simulations of nanoparticle-enhanced composites and fly- ash based foams that are being considered for the future generation naval structures or retrofitting of existing ones. In this study, the flexural/extensional dynamic modulus, damping, low-velocity impact and high-strain (Hopkinson bar) response of nylon ... |
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| Effect of Interface Structure on the Microstructural Evolution of Ceramics |
06 NOV 2007 |
19 pages |
| Authors:
Wook Jo; Doh-Yeon Kim; Nong-Moon Hwang; SEOUL NATIONAL UNIV (REPUBLIC OF KOREA) SCHOOL OF MATERIALS SCIENCE AND ENGINEERING
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| The interface atomic structure was proposed to have a critical effect on the microstructure evolution during sintering of ceramic materials. In liquid-phase sintering, spherical grains show the normal grain growth behavior without exception, while angular grains often grow abnormally. The coarsening process of spherical grains with a disordered or rough interface atomic structure is diffusion-controlled, because there is little energy barrier for atomic attachments. On the other hand, kink-generating sources ... |
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| The Effect of Holes on the Residual Strength of SiC/SiC Ceramic Composites (Preprint) |
Nov 2007 |
10 pages |
| Authors:
G Ojard; R Miller; Y Gowayed; U Santhosh; J Ahmaad; R John; PRATT AND WHITNEY EAST HARTFORD CT
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| Continued interest in ceramic matrix composites for the use in high temperature applications necessitates a comprehensive understanding of the effect of time-dependent loading in various environments on the material mechanical response. This understanding has to include the effect of structural features, such as holes, on the material performance. In this work, residual strength tests were conducted for samples with 2.286, and 4.572 mm diameter holes, located at the center of ... |
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| Simulation Studies of a Four Component Model of Zr-based Bulk Metallic Glass |
18 OCT 2007 |
14 pages |
| Authors:
Dan Miracle; Peter Harrowell; Julian R. Fernandez; SYDNEY UNIV (AUSTRALIA) SCHOOL OF CHEMISTRY
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| The objective of the work was to carry out simulation studies on the 5 component Vitreloy-1 metallic glass. This was to include the characterization of interaction potentials and the running of preliminary simulation calculations. One specific goal was to compare the outcomes of these calculations with the prediction of a crystal-based structural approximation to the amorphous state recently proposed by Miracle. To this end, a computational characterization of the Miracle ... |
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| Consolidation of A12O3 Nano-Power by Magnetic Pulsed Compaction and Sintering |
16 OCT 2007 |
13 pages |
| Authors:
Whung W. Kim; KOREA ATOMIC ENERGY RESEARCH INST DAEJEON NUCLEAR MATERIAL TECHNOLOGY DEVELOPMENT TEAM
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| Successful ulta-fine nano Al2O3 powder was consolidated and sintered using magnetic pulsed compaction. Measurements indicated that many properties in the consolidated Al2O3 bulk have been much improved over the conventional polycrystalline materials. The optimization of the compaction parameters and sintering conditions will lead to the consolidation of Al2O3 nanopowder for the higher density and even further enhanced mechanical properties. |
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| Tensile Creep and Fatigue of Sylramic-iBN Melt-Infiltrated SiC Matrix Composites: Retained Properties, Damage Development, and Failure Mechanisms (Preprint) |
Oct-2007 |
32 pages |
| Authors:
Robert Miller; Reji John; Yasser Gowayed; Gregory N Morscher; Greg Ojard; Unni Santhosh; Jalees Ahmed; PRATT AND WHITNEY EAST HARTFORD CT
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| The elevated temperature creep, fatigue, rupture, and retained properties of ceramic matrix composites envisioned for use in gas turbine engine applications are essential properties to understand and model for the purposes of component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system: the Sylramic-iBN woven fiberreinforced, BN interphase, melt-infiltrated SiC matrix composite, a wide variety of tensile creep, dwell ... |
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| Unusual Nature of NanoDomains in Ultrahigh Temperature Polymer Derived Ceramics |
25 SEP 2007 |
12 pages |
| Authors:
Rishi Raj; COLORADO UNIV AT BOULDER DEPT OF MECHANICAL ENGINEERING
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| This grant has the objective of explaining the unusual properties of polymer-derived-ceramics (PDCs), so called because they are made directly from cross-linked polymers by controlled pyrolysis. The PDCs have unusual properties: (i) They remain structurally and chemically stable up to 1500 degrees C, (ii) They are amorphous in Bragg diffraction although small-angle-x ray-scattering shows the presence of nanodomains, (iii) POCs do NOT show steady state creep despite their amorphous structure, ... |
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| Various Ceramics in Multilayer Composite Ground Vehicle Armor |
17 SEP 2007 |
12 pages |
| Authors:
Douglas N. Rose; Elena Bankowski; Mike Clauson; ARMY RESEARCH DEVELOPMENT AND ENGINEERING COMMAND WARREN MI
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| These briefing charts describe the use of various ceramics in multilayer composite ground vehicle armor. One material that is planned for pilot production is silicon nitride as a material solution for pellets in a pellet armor approach to ground vehicle armor. One of the pilot program's aims is cost reduction, from $200/Kg to $20/Kg. As described in filed patents, armor constructed of assembled ceramic pellets suspended in a matrix binder ... |
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| Cyclic Creep and Recovery Behavior of Nextel(Trademark) 720/Alumina Ceramic Matrix Composite at 1200deg C in Air and in Steam Environments |
SEP 2007 |
164 pages |
| Authors:
Bridgett A. Whiting; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The cyclic creep and recovery behaviors of the N720/Al2O3 composite were investigated in this research. The ceramic matrix composite (CMC) contains a porous alumina matrix with laminated, woven mullite/alumina (NextelTM 720) fibers. The composite does not have an interface between the fiber and matrix. The CMC relies on the porous nature for flaw tolerance. The objective of this study the influences of monotonic creep and cyclic creep loading histories on ... |
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| Laboratory Characterization of Solid Grade SW Brick |
AUG 2007 |
88 pages |
| Authors:
Erin M. Williams; Stephen A. Akers; Paul A. Reed; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| Personnel of the Geotechnical and Structures Laboratory, U.S. Army Engineer Research and Development Center, conducted a laboratory investigation to characterize the strength and constitutive property behavior of solid Grade SW brick. A total of 37 mechanical property tests were successfully completed, consisting of two hydrostatic compression tests, four unconfined compression (UC) tests, 12 triaxial compression tests (TXC), two constant mean normal stress tests, four direct pull (DP) tests, two uniaxial ... |
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| Laboratory Characterization of Gray Masonry Concrete |
AUG 2007 |
99 pages |
| Authors:
Erin M. Williams; Stephen A. Akers; Paul A. Reed; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| Personnel of the Geotechnical and Structures Laboratory, U.S. Army Engineer Research and Development Center, conducted a laboratory investigation to characterize the strength and constitutive property behavior of a gray masonry concrete. A total of 38 mechanical property tests were successfully completed: two hydrostatic compression tests, four unconfined compression (UC) tests, 16 triaxial compression (TXC) tests, two uniaxial strain tests, two uniaxial strain load/biaxial strain unload tests, five uniaxial strain load/constant ... |
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| High Temperature Liquid and Glass Precursors for Oxyphosphate Ceramic Composites |
JUL 2007 |
27 pages |
| Authors:
William T. Petuskey; ARIZONA STATE UNIV TEMPE DEPT OF CHEMICAL AND BIOENGINEERING
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| The overall objective of this project has been explore the structure, dynamics and physical chemistry of rare earth aluminophosphosilicates (REAPS) glasses for the purpose of designing low temperature synthetic routes for fabricating high temperature, high fracture toughness ceramic-matrix-composites. The concept is based on a glass-ceramic approach that combines the densification of glass powders via viscous sintering followed by independent crystallization anneals. The challenge with REAPS glasses is to balance the ... |
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| Analysis of Shock and High-Rate Data for Ceramics: Strength and Failure of Brittle Solids |
JUL 2007 |
48 pages |
| Authors:
Dennis E. Grady; APPLIED RESEARCH ASSOCIATES INC ALBUQUERQUE NM
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| Ceramics based on composition of the light intermetallic compounds, have demonstrated considerable success as a barrier material in armor applications. The exceptional strength-to-density ratio of ceramic plays a crucial role in the positive performance of ceramics in the terminal ballistic environment. Even the higher density ceramics, such as tungsten based materials, show promising behavior in space-limited armor applications. The implementation, optimization and evaluation of ceramic in armor systems benefit from ... |
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| Aqueous-Based Extrusion Fabrication of Ceramics on Demand |
Jul 2007 |
13 pages |
| Authors:
Michael S Mason; Tieshu Huang; Robert G Landers; Ming C Leu; Gregory E Hilmas; Michael W Hayes; MISSOURI UNIV-ROLLA
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| Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic slurries of high solids loading layer by layer for part fabrication. The material reservoir in a previously developed system has been modified to allow for starting and stopping of extrusion process on demand. Design pros and cons are examined and a comparison between two material reservoir designs is made. Tests were conducted to determine the optimal deposition parameters for ... |
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| Extending the Performance of Net Shape Molded Fiber Reinforced Polymer Composite Valves for Use in Internal Combustion Engines |
JUN 2007 |
367 pages |
| Authors:
Richard T. Buckley; COLORADO STATE UNIV FORT COLLINS DEPT OF MECHANICAL ENGINEERING
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| Fiber Reinforced Composite (FRC) materials offer the possibility of reduced mass and increased performance over metals. Used in internal combustion engines, this may enable increased power and mechanical efficiency. Previous work has both shown structural and thermal limitations. A net-shape resin transfer molded intake valve has been developed, using a single-piece carbon fiber preform and the high temperature polymer PETI-RFI. Performance has been validated through testing. High engine load conditions ... |
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| Evaluation Criteria for Aged Asphalt Concrete Surfaces |
JUN 2007 |
73 pages |
| Authors:
Haley P. Bell; Reed B. Freeman; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| An evaluation of aged asphalt concrete (AC) was performed during the period February to December 2006 at the Vicksburg Airport (Vicksburg, MS), Hood Army Airfield and Robert Gray Army Airfield (Fort Hood, TX), Lawson Army Airfield (Fort Benning, GA), Cairns Army Airfield (Fort Rucker, AL), Butts Army Airfield (Fort Carson, CO), and Kandahar Airfield (Kandahar, Afghanistan) to develop a method for predicting the performance of aged AC surfaces in situ. ... |
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| Combinatorial Production and Processing of Oxide Nanopowders for Transparent, Ceramic Lasers |
JUN 2007 |
86 pages |
| Authors:
Richard M. Laine; Stephen C. Rand; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Since the discovery of transparent polycrystalline alumina by Coble in 1962, transparent and translucent alumina and yttria based ceramics have achieved a significant presence in our everyday lives because of their utility in sodium (and metal halide) vapor lamp envelopes used for example in street lights (automotive lighting). More recently, transparent ceramic scintillators have replaced photographic film in most medical X-ray imaging equipment. Although known for 30 years, transparent ceramic ... |
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| Advanced Metals and Ceramics for Armor and Anti-Armor Applications. High-Fidelity Design and Processing of Advanced Armor Ceramics |
Jun 2007 |
124 pages |
| Authors:
D E Niesz; J W McCauley; RUTGERS - THE STATE UNIV PISCATAWAY NJ
|
| This is the final summary report of a 5-year (2001 2005) collaborative research program on advanced metals and ceramics for armor and anti-armor applications carried out in the U.S. Army Research Laboratory Material Center of Excellence at Rutgers and Johns Hopkins Universities under a cooperative-agreement contractual relationship. The focus of this center is on high-fidelity design and processing of advanced armor ceramics. The overarching goal has been to develop an ... |
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| The Effects of Environment on the Interlaminar Shear Performance of an Oxide/Oxide Ceramic Matrix Composite at Elevated Temperature |
Jun 2007 |
184 pages |
| Authors:
Patrick D Laffey; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This research investigated the interlaminar shear performance of an oxide/oxide ceramic matrix composite consisting of Nextel (trademark) 720 fibers in a high purity, porous alumina (Al2O3) matrix. The interlaminar shear performance was observed in both tension and compression of double notched specimens (DNS) at 1200 C. Interlaminar shear creep behavior was examined in both laboratory air and in steam environment at 1200 C. In air, the creep stress was -6.5 ... |
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| A Model for the Oxidation of Refractory Diborides (Preprint) |
May 2007 |
25 pages |
| Authors:
T A Parthasarathy; Ronald J Kerans; M Opeka; UES INC DAYTON OH
|
| Hypersonic applications require materials that can withstand very high temperatures. Refractory diborides appear to be the most promising candidates for these applications, from the standpoint of resistance to oxidation and evaporative loss. In this work, a mechanistic model is presented that predicts the oxidation behavior of diborides of Zr, Hf and Ti. Using available thermodynamic data and literature data on vapor pressures, good correspondence is obtained between theory and experiments ... |
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| Modeling Damage and Fragmentation in Concrete |
APR 2007 |
22 pages |
| Authors:
John D. Clayton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| A theory combining nonlinear continuum elasticity, inelasticity, thermodynamics, damage mechanics, and fragmentation is formulated. The model is applied to study concrete subjected to high rate loading as occurs during ballistic impact. Two thermodynamically motivated methods are postulated within this theoretical framework for quantitatively characterizing the mass and velocity distributions of the post-impact debris field, one based upon a local energy balance and a second following global entropy maximization. Here the ... |
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| Effect of Al Addition on Glass Forming Stability of Ca-Mg-Zn-Cu Based Bulk Metallic Glasses (PREPRINT) |
APR 2007 |
21 pages |
| Authors:
O. N. Senkov; J. M. Scott; Daniel B. Miracle; UES INC DAYTON OH
|
| The effect of Al addition on glass forming ability and glass stability of Ca-Mg-Zn, Ca-Mg-Cu, and Ca-Mg-Zn-Cu alloys was studied. The glassy alloys were produced by a copper mold casting method as wedge-shaped samples with thicknesses varying from 0.5 mm to 10 mm. Thermal properties, such as the glass transition, crystallization and melting temperatures, as well as heats of crystallization and melting, were determined for the produced glasses. Partial substitution ... |
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| Mechanical Properties of MI SiC/SiC Composites and Their Constituents (Preprint) |
APR 2007 |
22 pages |
| Authors:
Y. Gowayed; G. Ojard; R. Miller; U. Santhosh; J. Ahmad; R. John; AUBURN UNIV AL
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| A series of 15 melt infiltrated SiC/SiC composites were fabricated per the standard process arrived at by NASA-GRC (01/01 material). This was done based on the in-situ boron nitride process prior to fiber interface coating and subsequent densification. A series of physical property testing was conducted to determine the mechanical properties, cyclic load response, damage progression, and the effect of temperature on elastic properties. Other tests addressed properties that are ... |
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| Requirements Driven UAV Development |
Apr-2007 |
13 pages |
| Authors:
Mark C Patterson; Anthony Brescia; ADVANCED CERAMICS RESEARCH TUCSON AZ
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| Over the past 5 years Advanced Ceramics Research (ACR) has established itself in the USA as a persistent producer of Tier II class UAVs with 2 gasoline systems in production and 1 electric sonobuoy launched system under development. The Tier II designation as defined by the U.S. Navy and Marine Corps typically refers to a short range tactical UAV with less than 12 hours flight duration and an operational altitude ... |
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| Laser-Induced Spall in Silicon Carbide |
Apr 2007 |
9 pages |
| Authors:
T J Holmquist; A A Wereszczak; NETWORK COMPUTING SERVICES INC MINNEAPOLIS MN
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| This article presents an alternative (or additional) test technique to investigate ceramic spall strength. The test uses a laser beam to produce the impact conditions for spall. The test configuration consists of a ceramic target covered by an opaque material (usually black tape) followed by a transparent material (usually water). The laser first passes through the water and vaporizes a thin layer of the black tape. The vapor absorbs the ... |
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| Failure Pattern Formation in Brittle Ceramics and Glasses |
Apr 2007 |
12 pages |
| Authors:
Michael A Grinfeld; James W McCauley; Scott E Schoenfeld; Tim W Wright; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| When a high-speed projectile impacts a brittle material, such as glass or polycrystalline ceramic, severe damage and fragmentation is normally observed before projectile penetrates. AlON is a material being considered for a variety of transparent armor, sensor window, and radome applications. It is a polycrystalline ceramic that fulfills the requirements of transparency and requisite mechanical properties for transparent armor against armor piercing ammunition. AlON has a cubic, spinel crystal structure ... |
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| Mode I and Mode II Interlaminar Crack Growth Resistances of Ceramic Matrix Composites at Ambient Temperature |
02 MAR 2007 |
39 pages |
| Authors:
Sung R. Choi; Robert W. Kowalik; Donald J. Alexander; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
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| Interlaminar crack growth resistances were determined for five different SiC fiber-reinforced ceramic matrix composites (CMCs) including three gas-turbine grade melt-infiltrated SiC/SiC composites. Modes I and II crack growth resistances, GI and GII, were evaluated at ambient temperature using double cantilever beam and end notched flexure methods, respectively. The CMCs exhibited GI =200-500 J/m2 and GII=200-900 J/m2. Most of the CMCs, except the SiC/CAS composite, showed rising R-curve behavior either in ... |
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| A Study of Pre-Stress Effect on Dynamic Failure of Transparent Brittle Materials |
MAR 2007 |
19 pages |
| Authors:
G. I. Kanel; S. V. Razorenov; A. S. Savinykh; G. S. Bezruchko; G. V. Garkushin; G. E. Ivanchikhina; RUSSIAN ACADEMY OF SCIENCES MOSCOW INST FOR HIGH ENERGY DENSITIES
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| The report presents results of studying the pre-stress effect on dynamic failure of K8 crown glass, K14 crown glass, fused quartz and sapphire crystals. A technology of radial pre-compression of glass samples has been worked out. Controlled confinement pressure on the specimen in a range of 150 MPa to 550 MPa was provided by installing a shrink-fit metal sleeve on the lateral surface of the glass specimen disk. Results of ... |
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| Thermal Applications for Advanced Metallic Materials (Preprint) |
JAN 2007 |
13 pages |
| Authors:
Jonathan E. Spowart; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| Various applications for advanced metallic materials in the area of thermal management of potential interest to the United States Air Force are discussed. Particular emphasis is given to the following technologies; passive thermal systems utilizing high thermal conductivity metallic composites; lightweight metallic phase-change materials for managing thermal transients; high-efficiency thermoelectric materials for energy harvesting applications. In this paper, a brief background of the current SOA in each technology is presented, ... |
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Ceramics, Refractories and Glass
