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Displaying 926 - 950 of 1322

Recent Developments in the Characterization of Anisotropic Void Populations in Thermal Barrier Coatings Using Ultra-Small Angle X-ray Scattering

January 1, 2003
Author(s)
Gabrielle G. Long, T A. Dobbins, Andrew J. Allen, J Ilavsky, P Jemain, A Kulkarni, H Herman
Thermal barrier coatings (TBC) have complex void microstructures which control their in service properties. In the research reported here, ultra-small-angle X-ray scattering (USAXS) has been used to characterize anisotropic void populations in TBC s. A new

Subsolidus Phase Equilibria and Crystal Chemistry in the System BaO-TiO 2 -Ta 2 O 5

January 1, 2003
Author(s)
Terrell A. Vanderah, Robert S. Roth, T Siegrist, W Febo, J. M. Loezos, Winnie K. Wong-Ng
Subsolidus phase relations have been determined for the BaO: TiO 2Ta 2O 5 system. Approximately 100 specimens were prepared in air at temperatures near but below the solidus (1275 C to 1500 C). For the binary BaO: Ta 2O 5 subsystem, the formation of all

The Local Structure of Antimony in High Dose Antimony Implants in Silicon by XAFS and SIMS

January 1, 2003
Author(s)
M A. Sahiner, S W. Novak, Joseph Woicik, Y. Takamura, P B. Griffin, J D. Plummer
One of the important challenges in semiconductor industry is to sustain high concentration of dopant atoms electronically active in very small areas. In investigating the optimum post implantation treatment methods that will help to attain these conditions

Wear in Boundary Lubrication

January 1, 2003
Author(s)
Stephen M. Hsu, R G. Munro, M C. Shen
Wear studies under lubricated conditions can be classified into two nominally distinct categories: investigations of thewear mechanisms active within the material, and studies of the degradation mechanisms active within the lubricant. Thetwo categories

Wear of Hydroxyapatite Sliding Against Glass-Infiltrated Alumina

January 1, 2003
Author(s)
Sergei Kalinin, B Hockey, S Jahanmir
The present work reports on the processes involved in the wear of hydroxyapatite sliding against slip-cast, glass-infiltrated alumina. Synthetic hydroxyapatite is used as a model material representing tooth enamel, while the alumina that was used is

Wear Transitions and Tribochemical Reactions in Ceramics

January 1, 2003
Author(s)
S Jahanmir
Structural ceramics are used in diverse tribological applications due to their unique properties that include resistance to abrasion and erosion, resistance to corrosive wear, wear resistance at elevated temperatures, low density, and unique electrical

Weibull Strength Scaling for Standardized Rectangular Flexure Specimens

January 1, 2003
Author(s)
George D. Quinn
Formulas for the effective volumes and effective surfaces for rectangular bars loaded in flexure are reviewed. The ratio of strengths from any two configurations, such as 3-point flexural to 4-point, is independent of whether the flaws are volume or

Direct Separation of Short Range Order in Intermixed Nanocrystalline and Amorphous Phases

December 1, 2002
Author(s)
Charles E. Bouldin, A I. Frenkel, A V. Kolobov, I K. Robinson, J O. Cross, Y Maeda
Diffraction Anomalous Fine Structure (DAFS) and Extended X-Ray Absorption Fine Structure (EXAFS) measurements have been combined to determine short-range order (SRO) about a single atomic type in a sample of mixed amorphous and nanocrystalline phases

Microstructure-Based Simulation of Thermomechanical Behavior of Composite Materials by Object-Oriented Finite Element Analysis

December 1, 2002
Author(s)
N Chawla, B V. Patel, M Koopman, K K. Chawla, R Saha, B R. Patterson, Lin-Sien H. Lum, Stephen A. Langer
While it is well recognized that microstructure controls the physical and mechanical properties of a material, the complexity of the microstructure often makes it difficult to simulate by analytical or numerical techniques. In this paper we present a

Multiple Small-Angle Neutron Scattering Studies of Anisoptropic Materials

December 1, 2002
Author(s)
Andrew J. Allen, Norman F. Berk, J Ilavsky, Gabrielle G. Long
Various authors have recognized the power of multiple small-angle neutron scattering (MSANS) analysis in providing information on coarse, concentrated microstructures involving micrometer length-scales larger than are accessible in conventional small-angle

Analysis of the Isoelectric Point in Moderately Concentrated Alumina Suspensions Using Electroacoustic and Streaming Potential Methods

November 1, 2002
Author(s)
Vincent A. Hackley, J Patton, Lin-Sien H. Lum, R Wasche, H Abe, M Naito, Y Hotta, H Pendse
Alumina suspended in aqueous electrolytic solution was used as a model ceramic suspension to investigate the measurement precision and influencing factors for the determination of the isoelectric point (IEP) in moderately concentrated systems. Techniques

Talking Ceramics

November 1, 2002
Author(s)
Terrell A. Vanderah
This is an invited Perspective article describing the technical needs and state-of-the-art research activities in the materials science of microwave ceramics, especially dielectric materials which serve as critical elements in resonators and filters

Dynamic Analysis of Sliding Contacts at Head-Disk Interface

October 1, 2002
Author(s)
Tze J. Chuang, Stephen M. Hsu
As magnetic data storage technology moves towards higher areal data density with higher rotational speeds and lower flying heights, the propensity of severe sliding contacts at the head-disk interface is bound to increase. The tribological performance of

Nanopowder Characterization: Challenges and Future Directions

October 1, 2002
Author(s)
Ajitkumar Jillavenkatesa, J F. Kelly
This manuscript summarizes the proceedings and conclusions of a workshop organized to address issues associated with particle size and size distribution characterization of nanaopowders. Presentations made during this workshop highlighted the strengths and

Semifluorinated Aromatic Side-Group Polystyrene-Based Block Copolymers: Bulk Structure and Surface Orientation Studies

October 1, 2002
Author(s)
X Li, L Andruzzi, E Chiellini, Giancarlo Galli, Christopher K. Ober, A Hexemer, E K. Kramer, Daniel A. Fischer
Two families of narrow polydispersity poly(styrene)-based block copolymers bearing side groups containing both a phenyl ring and a para-linked semifluorinated side group were designed to produce stable low energy surfaces. The effects of the phenyl ring on

Structural Study of an Unusual Cubic Pyrochlore Bi 1.5 Zn o.92 Nb 1.5 O 6.92

October 1, 2002
Author(s)
Igor Levin, T G. Amos, J Nino, Terrell A. Vanderah, C A. Randall, M T. Lanagan
Single-phase pyrochlore specimens of Bi 1.5Zn 0.92Nb 1.5O 6.92 were studied using combined electron, X-ray and neutron powder diffraction techniques. Rietveld refinements using neutron powder diffraction data confirmed an average pyrochlore structure A 2B

The 2001 Material Research Society (MRS) Fall Meeting Report

September 17, 2002
Author(s)
Winnie K. Wong-Ng
The 2001 Materials Research Society (MRS) annual meeting took place in Boston Copely Plaza (in the spacious Hynes Convention Center) from November 25-30. The four meeting co-chairs: B.M. Clemens, J.A. Floro, J.A. Kornfield, and Y. Suzuki have organized a

Crack Growth in Soda-Lime Silicate Glass Near the Static Fatigue Limit

September 1, 2002
Author(s)
Sheldon M. Wiederhorn, A Dretzke, J Rodel
The atomic force microscope (AFM) was used to explore the nature of features formed on the surfaces of cracks in soda-lime-silicate glass that were held at stress intensity factors below the crack growth threshold. All studies were conducted in water
Displaying 926 - 950 of 1322
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