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Displaying 1601 - 1625 of 1721

Single Fiber Composites: A New Methodology for Determining Interfacial Shear Strength

January 1, 2000
Author(s)
Gale A. Holmes, Donald L. Hunston, Walter G. McDonough, R C. Peterson
One of the critical factors controlling the long-term performance and durability of composites in structural applications is the interfacial shear strength (IFSS). The single fiber composite (SFC) test has been viewed by many as the best test for

The Effect of Processing on Interfacial Shear Properties of Composite Materials

January 1, 2000
Author(s)
Walter G. McDonough, Joy P. Dunkers, Gale A. Holmes, Richard~undefined~undefined~undefined~undefined~undefined Parnas
The objective of our research was to extend the use of the single fiber fragmentation test to include fast reacting resin systems and to determine the effect of gelation time on interfacial shear properties. To do this work, we developed a processing

Ordering/Displacive Phase Transformations in Ca 4 Nb 2 O 9

December 17, 1999
Author(s)
Igor Levin, Leonid A. Bendersky, Robert S. Roth, Terrell A. Vanderah
Four Ca 4Nb 2O 9=Ca(Ca1/3Nb 2/3)O 3 polymorphs based on ABO 3 perovskite-like structure were identified. These polymorphs feature three different arrangements of Ca/Nb cations on B-sites of perovskite. In three of the polymorphs, cation ordering is

Modeling Wear of Ceramics Based on Wear Maps

December 2, 1999
Author(s)
Stephen M. Hsu, M C. Shen
Ceramics are increasingly being considered for wear resistant applications. The design and prediction of ceramics wear, however are lacking behind metals. This paper addresses the ability to predict wear of ceramics by examining a large data base of four

A Novel Multiaxial Wear Tester for Accelerated Testing of Materials

December 1, 1999
Author(s)
M C. Shen, Stephen M. Hsu, John A. Tesk, A Christou
A versatile wear tester has been designed and built. The initial study showed that that with this tester, tes procedures can be developed to achieve clinically relevant simulations in a short time. With the continuously monitored force traces, this tester

Combined EXAFS and First-Principles Theory Study of Pb 1-x Ge x Te

December 1, 1999
Author(s)
Bruce D. Ravel, Eric J. Cockayne, E Newville, K M. Rabe
The narrow band-gap semiconductor Pb 1-xGe xTe has a low-temperature ferroelectric rhombohedral phase whose average structure is a distorted rocksalt structure. We have measured the Extended X-Ray-Absorption Fine-Structure (EXAFS) spectra of Pb 1-xGe xTe

Cyclic Fatigue of Intrinsically Brittle Ceramics in Contact with Spheres

December 1, 1999
Author(s)
D K. Kim, Yeon-Gil G. Jung, I M. Peterson, Brian R. Lawn
Contact damage modes in cyclic loading with spheres are investigated in three relatively brittle ceramics, soda-lime glass, porcelain and fine-grain silicon nitride, in moist environments. Initial damage at small numbers of cycles and low loads consists of

Determination of Texture From Individual Grain Orientation Measurements

November 17, 1999
Author(s)
J Blendell, Mark D. Vaudin, Lin-Sien H. Lum
We present a technique for determining the texture of a polycrystalline material based on the measurement of the orientation of a number of individual grains. We assume that the sample has fiber texture and that the texture can be characterized by a

High-Temperature Properties of Liquid-Phase-Sintered A-Sic

November 1, 1999
Author(s)
R P. Jensen, William E. Luecke, N P. Padture, Sheldon M. Wiederhorn
We have characterized the high-temperature subcritical crack growth and oxidation resistance of a liquid-phase-sintered (LPS) SiC with 20% volume fraction yttrium aluminum garnet (YAG) second phase. Constant stress rate testing in air in the temperature

Small Angle Neutron Scattering of Solutions of Arborescent Graft Polymers

November 1, 1999
Author(s)
S M. Choi, R M. Briber, Barry J. Bauer, A Topp, M Gauthier, L Tichagwa
Small angle neutron scattering was used to measure the size and shape of arborescent graft polymers as a function of generation number in solution. The radius of gyration of arborescent graft polymers was found to be almost independent of temperature in

Scratch Damage in Zirconia Ceramics

October 25, 1999
Author(s)
S K. Lee, Rajan Tandon, M Readey, Brian R. Lawn
Scratch damage modes in zirconia-based ceramics, Mg-PSZ, T-TZP and Ce-TZP are investigated. Precursor indentation tests with a tungsten carbide sphere foreshadow the nature of damage: in Mg-PSZ - extensive quasi-plastic deformation in the region outside

Anisotropic Small-Angle Neutron Scattering Studies of Ceramics

October 1, 1999
Author(s)
Andrew J. Allen, Lin-Sien H. Lum, K T. Faber, M H. Zimmerman, Jay S. Wallace
This paper discusses how small-angle neutron scattering studies can be applied in two variations to obtain a representative characterization of the large, densely-populated, and anisotropic features that occur in the microstructures of various materials

Application of the Three O Method to a Film on a Substrate of Finite Thickness

October 1, 1999
Author(s)
J Y. Kim, A Feldman, Donald B. Novotny
The three omega thermal conductivity measurement method is analyzed for the case of one or more thin films on a substrate of finite thickness. The analysis is used to obtain the thermal conductivities of SiO 2 films on Si substrates and of a chemical vapor

Chemo-Mechanical Machining of Ceramics

October 1, 1999
Author(s)
Richard S. Gates, Stephen M. Hsu
Chemically assisted machining of ceramics is a way to remove ceramic materials rapidly using chemical reactions at the interface between the tool and the workpiece. Two effects are observed: chemical reactions that react with he workpiece forming an easily

XPS Study of the Dehydration of Clay and Kaolin Powders

October 1, 1999
Author(s)
T N. Wittberg, P S. Wang
X-ray photoelectron spectroscopy (XPS) was used to analyze samples of a commercial clay powder and a kaolin standard. Samples were analyzed both in the as-received condition and after heating to temperatures > or = to} 750 degrees C. There was a loss of
Displaying 1601 - 1625 of 1721