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Displaying 2101 - 2125 of 2146

The Application of Optical Coherence Tomography to Problems in Polymer Matrix Composites

January 1, 2001
Author(s)
Joy Dunkers, Frederick R. Phelan Jr., D P. Sanders, M J. Everett, William H. Green, Donald L. Hunston, Richard~undefined~undefined~undefined~undefined~undefined Parnas
The Composites Group at the National Institute of Standards and Technology has found optical coherence tomography (OCT) to be a powerful tool for non-destructive characterization of polymer matrix composites. Composites often exhibit superior properties to

Using Self-Assembled Monolayer Technology to Probe the Fiber-Matrix Interface

January 1, 2001
Author(s)
Gale A. Holmes, E Feresenbet, D T. Raghavan
hesion at the fiber matrix interface of composite specimens is often ascribed to the following factors (Sharpe and Drzal): (1) mechanical interlocking, (2) physicochemical interactions, (3) chemical bonding, and (4) mechanical deformation of the fiber

1,6-Hexanedithiol Monolayers on Au(111): A Multi-Technique Structural Study

December 29, 2000
Author(s)
T Leung, M Gerstenberg, D J. Lavrich, G Scoles, F Schreiber, G Poirier
Monolayers of 1,6-hexanedithiol [HS(CH 2) 6SH] deposited on Au(111) from the gas phase were characterized by scanning tunneling microscopy (STM), grazing incidence X-ray diffraction (GIXD), and low energy atom diffraction (LEAD). Molecular resolution STM

Phase Equilibria and Dielectric Behavior in the CaO:Al 2 O 3 :Nb 2 O 5 System

November 1, 2000
Author(s)
Terrell A. Vanderah, W Febo, Julia Y. Chan, Robert S. Roth, J. M. Loezos, L D. Rotter, Richard G. Geyer, B A. Reisner, Dennis B. Minor
Subsolidus phase equilibria in the CaO:Al2O3:Nb2O5 system at 1325 C in air have been determined. One ternary phase forms, Ca2AlNbO6, which exhibits a perovskite-related structure with 1:1 or NaCl-type ordering of Al3+ and Nb5+ on the B-sites. Indexed X-ray

Structural Study of Ba 11 Fe 8 Ti 9 O 41 by X-Ray Diffraction

September 1, 2000
Author(s)
T Siegrist, C Svensson, Terrell A. Vanderah, Robert S. Roth
The crystal structure of Ba 11Fe 8Ti 9O 41 was determined using single-crystal and powder X-ray diffraction nethods. This new phase crystallizes in the hexagonal space group P6 3/mmc (No 194) (a=5.7506(3) , c=61.413(2) ; Z=2; Pcalc=5.75 g/cm 3) and

Phonons and Static Dielectric Constant in CaTiO 3 From First Principles

August 1, 2000
Author(s)
Eric J. Cockayne, Benjamin P. Burton
CaTiO 3 has a static dielectric constant that extrapolates to a value greater than 300 at zero temperature. We investigate the origin of this large dielectric response on a microscopic level, using first-principles plane-wave pseudopotential density

A Test Method for Assessing Interfacial Shear Strength in Composites

May 1, 2000
Author(s)
Gale A. Holmes, Donald L. Hunston, Walter G. McDonough, R C. Peterson
Two of the critical factors controlling the long-term performance and durability of composites in structural applications is the fiber-matrix interfacial shear strength (IFSS) and the durability of the fiber-matrix interface. The single fiber fragmentation

Imaging of Composite Defects and Damage Using Optical Coherence Tomography

May 1, 2000
Author(s)
Joy Dunkers, M J. Everett, D P. Sanders, Donald L. Hunston
The Composites Group at the National Institute of Standards and Technology has found optical coherence tomography (OCT) to be a powerful tool for non-destructive characterization of polymer matrix composites. Composites can be made more cost competitive by

X-Ray Topography Study of Surface Damage in Single-Crystal Sapphire

February 9, 2000
Author(s)
David R. Black, Robert S. Polvani, Kate Medicus, H E. Burdette
X-ray diffraction topography was used to investigate the relationship between sub-surface damage, near-surface microstructure, and fracture strength in a series of sapphire modulus of rupture (MOR) bars which had been fabricated to proof test fabrication

Imaging of Impact Damage in Composites Using Optical Coherence Tomography

February 1, 2000
Author(s)
Joy Dunkers, D P. Sanders, Donald L. Hunston, M J. Everett
Resistance to impact damage is extremely important for most composites. Such damage can initiate delamination, one of the most common failure modes in composites.. Because this is such an important failure mode, many studies have tried to develop matrix

Secondary Ferrite Number Reference Materials: Gage Calibration and Assignment of Values

February 1, 2000
Author(s)
Christopher N. McCowan, Thomas A. Siewert, D P. Vigliotti, C M. Wang
Ferrite Numbers (FN) were assigned to blocks of stainless steel that serve as secondary ferrite reference materials (RM 8480 and 8481), and these specimens were placed in our Reference Materials inventory. These reference materials are used to calibrate

A Microshear Test to Measure the Bond Between Dental Composites and Dental Substrates

January 1, 2000
Author(s)
Walter G. McDonough, Joseph M. Antonucci, Gary E. Schumacher, Y Shimada
Mechanical property tests such as the diametral tensile, uniaxial tensile, biaxial flexural, shear, and transverse strength tests are commonly used for assessing the bond that forms between dental composites and dental substrates such as dentin and enamel

Factors That Affect Adhesion at the Fiber-Matrix Interface in Composites

January 1, 2000
Author(s)
Gale A. Holmes, E Feresenbet, E Pohl, Walter G. McDonough, D T. Raghavan, D Thompson
The development of methods to assess adhesion at the fiber-matrix interface in composite materials has been driven primarily by the recognition that the interface or interphase in many composite materials has a profound affect on the onset of failure in

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
Displaying 2101 - 2125 of 2146