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Displaying 1226 - 1250 of 1321

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

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

A new model for tensile creep of silicon nitride

October 1, 1999
Author(s)
William E. Luecke, Sheldon M. Wiederhorn
The tensile creep rate of most commercial grades of Si3N4 increases strongly with stress. Although the usual power-law functions can represent the creep data, the data often show curvature and systematic variations of slope with temperature and stress. In

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

Simulation of Diamond-Ground Surfaces

September 17, 1999
Author(s)
P Koshy, L K. Ives, S Jahanmir
State-of-the-art models available for predicting the characteristics of diamond-ground surfaces entail digitization of wheel topography which limits their practical utility. This paper presents a geometric simulation of surface generation in diamond

Structural investigation of (Sr 4-d Ca d )PtO 6 Using X-Ray Rietveld Refinement

August 16, 1999
Author(s)
Winnie K. Wong-Ng, James A. Kaduk, R A. Young, F Jiang
The structures of the solid solution series (Sr 4-δCa δ)PtO 6, with δ = 0, 0.85(1), 2, and 3, have been investigated using the Rietveld refinement technique with laboratory x-ray powder data. A complete solid solution between Sr and Ca was confirmed to

Apparent Correlation of Fracture Toughness and Strength

August 1, 1999
Author(s)
R G. Munro, Stephen W. Freiman
An extensive collection of fracture toughness (KIc) and strength ( f) data for brittle materials has been used to examine the relation between the mean measured values of KIc and f. The two properties have been found to have a weak, but useful, empirical

Micro-Mechanic Model for Cathodic Blister growth in Painted Steel

August 1, 1999
Author(s)
Tze J. Chuang, Tinh Nguyen, S K. Lee
A micro-mechanic blister growth model is proposed for a coating system consisting of a polymer film applied to a steel substrate exposed to salt solutions. The mechanism of the blister formation is based on corrosion-induced disbondment of the coating at

VARMAS After Twelve

July 1, 1999
Author(s)
George D. Quinn
The Versailles Advanced Materials and Standards VAMAS project is a forum for prestandardization research. It has helped spread awareness of new testing and characterization methods around the world. Technical Working Area (TWA) 3-Ceramics has been active

X-Ray-Absorption Edge Separation Using Diffraction Anomalous Fine-Structure

July 1, 1999
Author(s)
Bruce D. Ravel, Charles E. Bouldin, H Renevier, J -. Hodeau, J -. Berar
When two or more absorption edges in a material are sufficiently close in energy, Extended X-ray-Absorption Fine-Structure (EXAFS) spectroscopy may be of limited utility as the usable data range above the lower energy edge is truncated by the presence of

Standard Reference Material 2100: Ceramic Fracture Toughness

June 30, 1999
Author(s)
George D. Quinn, R J. Gettings, K Xu
A new Standard Reference Material (SRM) has been prepared for ceramic fracture toughness. It is the first reference material in the world for the property fracture toughness for any class material (metal, ceramic, polymer). The SRM may be used with any

Analysis of Residual Stress State in Thermal Barrier Coatings

June 1, 1999
Author(s)
Tze-Jer Chuang, Lin-Sien H. Lum
To enhance thermal efficiency of a system in high temperature structural applications, thermal barrier coatings (TBC) are often applied on the metallic substrate to protect the component from deterioration while increasing the operating temperature of the
Displaying 1226 - 1250 of 1321
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