NASA Scientific and Technical Aerospace Reports

of nanofiber agglomerates, to promote adequate dispersion in polyimide. Conductivity data on cast nanofiber filled polyimide
films are also presented.
Author
Carbon; Fibers; Kapton (Trademark); Polyimides; Product Development
20040111138 Lockheed Martin Corp., Syracuse, NY, USA
Single Step Lapping and Polishing Process for Achieving Surfaces of Compound Semiconductors with Atomic Flatness
using a Sub-micron Agglomerate-free Alumina Slurry
Dutta, P. S.; Rajagopalan, G.; Gutmann, R. J.; Keller, D.; Sweet, L.; Aug. 2002; 12 pp.; In English
Report No.(s): DE2004-821860; LM-02K071; No Copyright; Avail: Department of Energy Information Bridge
A novel approach for a single step lapping and final polishing of III-V and II-VI compounds using agglomerate-free
alumina slurries has been developed. The agglomerate-free nature of the sub-micron slurry leads to removal rates comparable
to conventional slurries (with larger particles of tens of microns) used for semiconductor lapping. Surfaces with minimal
surface damage and extremely low surface roughness have been obtained using the sub-micron slurries and a soft pad.
Strategies for post polishing surface cleaning have been discussed. The new methodology has been experimented on GaSb,
InAs, GaAs, InP, InSb, CdTe, GaInSb, GaInAs, AlGaAsSb, GaInAsSb and HgCdTe. Selected results of surface analyses of
GaSb and GaInSb using atomic force microscopy will be presented.
NTIS
Surface Roughness; Polishing; Slurries; Semiconductors (Materials)
20040111152 Lawrence Livermore National Lab., Livermore, CA
Synthesis and Characterization of Porous Hydroxyapatite and Hydroxyapatite Coatings
Nieh, T. G.; Choi, B. W.; Jankowski, A. F.; Oct. 25, 2000; In English
Report No.(s): DE2004-15005278; UCRL-JC-141229; No Copyright; Avail: National Technical Information Service (NTIS)
A technique is developed to construct bulk hydroxyapatite (HAp) with different cellular structures. The technique involves
the initial synthesis of nanocrystalline hydroxyapatite powder from an aqueous solution using watersoluble compounds and
then followed by spray drying into agglomerated granules. The granules were further cold pressed and sintered into bulks at
elevated temperatures. The sintering behavior of the HAp granules was characterized and compared with those previously
reported. Resulting from the fact that the starting HAp powders were extremely fine, a relatively low activation energy for
sintering was obtained. In the present study, both porous and dense structures were produced by varying powder morphology
and sintering parameters. Porous structures consisting of open cells were constructed. Sintered structures were characterized
using scanning electron microscopy and xray tomography. In the present paper, hydroxyapatite coatings produced by
magnetron sputtering on silicon and titanium substrates will also be presented. The mechanical properties of the coatings were
measured using nanoindentation techniques and microstructures examined using transmission electron microscopy.
NTIS
Scanning Electron Microscopy; Transmission Electron Microscopy; Mechanical Properties; Agglomeration; Magnetron
Sputtering
20040111188 Lawrence Livermore National Lab., Livermore, CA
Determination of Reactive Surface Area of Melt Glass
Bourcier, W. L.; Roberts, S.; Smith, D. K.; Hulsey, S.; Newton, L.; Oct. 01, 2000; In English
Report No.(s): DE2003-15005717; UCRL-ID-145181; No Copyright; Avail: National Technical Information Service (NTIS)
A comprehensive investigation of natural and manmade silicate glasses, and nuclear melt glass was undertaken in order
to derive an estimate of glass reactive surface area. Reactive surface area is needed to model release rates of radionuclides from
nuclear melt glass in the subsurface. Because of the limited availability of nuclear melt glasses, natural volcanic glass samples
were collected which had similar textures and compositions as those of melt glass. A flow-through reactor was used to measure
the reactive surface area of the analog glasses in the presence of simplified NTS site ground waters. A measure of the physical
surface area of these glasses was obtained using the BET gas-adsorption method. The studies on analog glasses were
supplemented by measurement of the surface areas of pieces of actual melt glass using the BET method. The variability of
the results reflect the sample preparation and measurement techniques used, as well as textural heterogeneity inherent to these
samples.
NTIS
Silica Glass; Melts (Crystal Growth); Surfaces; Radioactive Isotopes
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