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Displaying 26 - 46 of 46

Non-Cavitational Tensile Creep in Lu-Doped Silicon Nitride

January 1, 2002
Author(s)
F Lofaj, Sheldon M. Wiederhorn, Gabrielle G. Long, B Hockey, P R. Jemian, L Browder, April Andreas
The tensile creep behavior of a Lu-based silicon nitride, SN 281, was studied in the temperature range 1400 C to 1550 C with test periods of up to 10 000 h. Strain rates were 3 to 5 orders of magnitude less than those for Yb-based grades of silicon nitride

Dedication to Richard D. Deslattes

November 1, 2001
Author(s)
Ernest G. Kessler, Gabrielle G. Long
On May 16, 2001, the National Institute of Standards and Technology lost a most illustrious career scientist in x-ray research. This volume is dedicated to honor the memory of Richard D. Deslattes and his lifetime of achievments at NIST. Deslattes'

Microstructural Characterization Studies to Relate the Properties of Thermal Spray Coatings to Feedstock and Spray Conditions

September 1, 2001
Author(s)
Andrew J. Allen, Gabrielle G. Long, H Boukari, J Ilavsky, A Kulkarni, S Sampath, H Herman, A N. Goland
This paper reports how the microstructural information, obtainable for thick plasma-sprayed ceramic deposits by small-angle scattering can be used to explore the relationships among the feedstock or spray process conditions, the anisotropic void and crack

X-Ray Scattering and Imaging From Plastically Deformed Metals

July 1, 2001
Author(s)
Gabrielle G. Long, Lyle E. Levine, Richard J. Fields
New ultra-small-angle X-ray scattering (USAXS) facilities at 3rd generation synchrotron sources enjoy an additional 1 to 3 decades of X-ray brilliance over 2nd generation instruments, and can now quantify microstructural features from 3nm to 1.3 m in size

Tensile Creep in the Next Generation Silicon Nitride

January 1, 2001
Author(s)
F Lofaj, Sheldon M. Wiederhorn, Gabrielle G. Long, P R. Jemian
The tensile creep behavior of a Lu-containing silicon nitride (SN 281) was characterized in the temperature range of 1350oC to 1550oC for test periods up to 10000h. For the same test conditions, the minimum strain rates were several orders of magnitude

NIST Centennial Celebration - Crystallographic Highlights

December 1, 2000
Author(s)
Winnie K. Wong-Ng, Alan D. Mighell, Gabrielle G. Long, Leonid A. Bendersky, Vicky L. Karen, J D. Barnes, G L. Gilliland, T Gallagher, Terrell A. Vanderah, R G. Munro, Paul E. Stutzman, H F. McMurdie, S Block, Gasper J. Piermarini, Robert S. Roth, Antonio Santoro, Curt W. Reimann, C R. Hubbard, John W. Cahn, E Prince, D R. Lide, H Ondik, Lawrence P. Cook, T Siegrist, G DeTitta, L Finger, H Evans, E Gabe, G Enright, J T. Armstrong, M Levenson, Laurence C. Chow, Shozo Takagi, M Mathew, Jeffrey W. Lynn, H S. Peiser
NIST has a long history of crystallographic research, and has made significant contributions to the advancement of the fields of crystallography, biology, and materials science. The articles are contributed by scientists from various divisions at NIST, and

The Ultra-Small-Angle X-Ray Scattering Instrument on UNICAT at the APS

October 1, 2000
Author(s)
Gabrielle G. Long, Andrew J. Allen, J Ilavsky, P R. Jemian, P Zchack
A new ultra-small-angle X-ray scattering (USAXS) instrument has been commissioned as part of the UNICAT facility on the 33-ID line at the Advanced Photon Source. The instrument offers continuously-tunable optics for anomalous USAXS, 1000 times the

A Nanocomposite Poly(Methyl-Methacrylate) Bone Cement

July 1, 2000
Author(s)
A H. Gomoll, A Bellare, W Fitz, T S. Thornhill, R D. Scott, P R. Jemian, Gabrielle G. Long
Poly(methyl methacrylate) (PMMA) based orthopaedic bone cements contain 1-3 micro υ size radiopacifier particles. Incomplete dispersion of these particles leads to the presence of 50-200 micro υ size agglomerates. These large defects are sites of high

In-Situ Observation of Small-Angle X-Ray Scattering by Dislocations

June 1, 2000
Author(s)
Lyle E. Levine, Gabrielle G. Long, R Thomson
Ultra-small-angle X-ray scattering by dislocations in single-crystal aluminum has been observed in situ as a function of plastic deformation. The scattering is observed to be strongly dependent upon sample orientation, with single dislocations, dislocation

Microstructural Changes in YSZ Deposits During Annealing

March 1, 1999
Author(s)
Andrew J. Allen, J Ilavsky, Gabrielle G. Long, Jay S. Wallace, C C. Berndt, H Herman
Various methods have been applied to the microstructural characterization of thermally-sprayed depostis. However, coexisting anisotropic distributions of intra-splat cracks and interlamellar pores, and the broad size range of rounded globular pores, have

Morphology of Polyethylene-Carbon Black Composites

November 1, 1998
Author(s)
G Beaucage, Daniel A. Fischer, Gabrielle G. Long, S Rane, D W. Schaefer
Carbon black is a common polymer additive that is used for reforcement and for its ability to enhance physical properties such as conductivity. This paper pertains to a small-angle x-ray scattering [SAXS] study of a conductive grade of carbon black and

Multiple Small-Angle Neutron Scattering

September 1, 1998
Author(s)
Gabrielle G. Long, Susan Krueger, Andrew J. Allen
Over the past decade, a multiple small-angle neutron scattering (MSANS) formalism has been developed to enable researchers to derive microstructural parameters from multiply-scattered small-angle neutron data. The MSANS formalism is particularly useful in

Anisotropic Microstructure of Plasma-Sprayed Deposits

April 1, 1998
Author(s)
J Ilavsky, Gabrielle G. Long, Andrew J. Allen, L Leblanc, M Prystay, C Moreau, Alan H. Band
The microstructure of plasma-sprayed deposits [PSD] is dominated by two void systems-interlamellar pores and intralamellar cracks - each with a different anisotropy. Varying anisotropies and crack-to-pore ratios within PSDs are responsible for the

Small Angle Scattering by Dislocations

March 1, 1998
Author(s)
R Thomson, Lyle E. Levine, Gabrielle G. Long
It is shown that the small-angle scattering of x rays or neutrons by dislocations in a deformed metal, which are partially ordered into wall-like structures, is characterized by several structure factors. Principally there are associated with 1) a single

Evolution of the Microstructure of Plasma-Sprayed Deposits During Heating

January 1, 1998
Author(s)
Gabrielle G. Long, Andrew J. Allen, J Ilavsky
The evolution of the void microstructure of yttria-stabilized zirconia [YSZ] plasma-sprayed deposits [PSD] was studied as a function of heating in air from room temperature to 1400 C, and during a constant temperature hold at 1100 C for 19 hours. The

CAVITATION CONTRIBUTES SUBSTANTIALLY TO TENSILE CREEP IN SILICON NITRIDE

August 1, 1995
Author(s)
William E. Luecke, Sheldon M. Wiederhorn, B Hockey, Ralph Krause, Gabrielle G. Long
During tensile creep of a hot isostatically pressed (HIPed) silicon nitride, the volume fraction of cavities increases linearly with strain; these cavities produce nearly all of the measured strain. In contrast, compressive creep in the same stress and