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Metallic Particles (metallic + particle)
Selected AbstractsA General Process for the Fabrication of Air-Stable Metallic Particles (Cd, Zn and Al) by the Decomposition of Alkyl,Metal CompoundsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2008Aharon Gedanken Abstract The thermolysis of alkyl,metal compounds under autogenic pressure, with the three metals Cd, Zn, and Al as examples, suggest that this might become a general method for preparing a composite where the metal is the core and carbon the shell. The air-stability of these composites is also demonstrated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Development of an identification system for location of free metallic particles in GIS based on analysis of Lamb wavesELECTRICAL ENGINEERING IN JAPAN, Issue 3 2009Masahiro Kozako Abstract We investigated propagation properties of Lamb waves in a gas-insulated switchgear (GIS) tank to diagnose insulation performance of GIS. The acoustic signals excited by a free metallic particle colliding with the tank sheath were measured using AE sensors. The wavelet transform was applied to decompose the wave data into its time,frequency components. As a result, difference of propagation properties of Lamb waves is clearly seen with different sizes of GIS tank. Based on the characteristics of Lamb waves, algorithms for location identification of a free metallic particle were examined in model GIS using two AE sensors. Herein, we propose a new system for location identification of a free metallic particle in GIS. Moreover, it is verified that the new identification system is suitable as a diagnostic technique for GIS. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(3): 28,35, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20676 [source] Evidence of Nearest-Neighbor Ordering in Wet-Processed Zirconia,Nickel CompositesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2001Carlos Pecharromán Monolithic zirconia,nickel (ZrO2/Ni) cermets have been prepared by a wet-processing method with nickel volume concentrations of 16%,40%. Microstructural analysis performed on scanning electron microscopy images has revealed evidence of a partial ordering of metallic particles inside the ceramic matrix. This ordering does not appear in mullite/molybdenum cermets. Complex impedance measurements have shown that the percolation threshold of ZrO2/Ni cermets appears at a filling factor (fc) of 0.34, exceeding the theoretical value (fc= 0.16), as a consequence of its microstructural order. Electrical measurements display the expected increase of capacity near the percolation threshold. These results open the possibility to design new devices with the appealing electric, magnetic, and mechanical properties that are predicted by the percolation theory. [source] Microstructures of metal grains in ordinary chondrites: Implications for their thermal historiesMETEORITICS & PLANETARY SCIENCE, Issue 3 2000Hugues LEROUX Three ordinary chondrites, Saint Séverin (LL6), Agen (H5), and Tsarev (L6) were selected because they display contrasting microstructures, which reflects different thermal histories. In Saint Séverin, the microstructure of the Ni-rich metal grains is due to slow cooling. It consists of a two-phase assemblage with a honeycomb structure resulting from spinodal decomposition similar to the cloudy zone of iron meteorites. Microanalyses show that the Ni-rich phase is tetrataenite (Ni = 47 wt%) and the Ni-poor phase, with a composition of ,25% Ni, is either martensite or taenite, these two occurring adjacent to each other. The observation that the Ni-poor phase is partly fcc resolves the disagreement between previous transmission electron microscopy (TEM) and Mössbauer studies on iron meteorites and ordinary chondrite metal. The Ni content of the honeycomb phase is much higher than in mesosiderites, confirming that mesosiderites cooled much more slowly. The high-Ni tetrataenite rim in contact with the cloudy zone displays high-Ni compositional variability on a very fine scale, which suggests that the corresponding area was destabilized and partially decomposed at low temperature. Both Agen and Tsarev display evidence of reheating and subsequent fast cooling obviously related to shock events. Their metallic particles mostly consist of martensite, the microstructure of which depends on local Ni content. Microstructures are controlled by both the temperature at which martensite forms and that at which it possibly decomposes. In high-Ni zones (>15 wt%), martensitic transformation started at low temperature (<300 °C). Because no further recovery occurred, these zones contain a high density of lattice defects. In low-Ni zones (<15 wt%), martensite grains formed at higher temperature and their lattice defects recovered. These martensite grains present a lath texture with numerous tiny precipitates of Ni-rich taenite (Ni = 50 wt%) at lath boundaries. Nickel composition profiles across precipitate-matrix interfaces show that the growth of these precipitates was controlled by preferential diffusion of Ni along lattice defects. The cooling rates deduced from Ni concentration profiles and precipitate sizes are within the range 1,10 °C/year for Tsarev and 10,100 °C/year for Agen. [source] Preparation and characterization of crosslinked resins containing ferrite particlesPOLYMER ENGINEERING & SCIENCE, Issue 10 2008Luiz Claudio de Santa Maria Micrometer-sized magnetic particles hosted on network material were successfully prepared by a simple chemical process (ion exchange followed by co-precipitation) from commercial styrene-divinylbenzene copolymers. Energy dispersive X-ray spectroscopy (EDS) coupled to scanning electron microscopy (SEM) allowed the observation of submicron particles. All the produced spherical beads have presented metallic particles (NiFe2O4, CuFe2O4, CoFe2O4, or MnFe2O4), either as isolated particles or agglomerates, located on their external and internal (within pores) The thermal stability of the composites, evaluated by thermogravimetric techniques, were found to be dependent on the amount of ferrite particles incorporated into them. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers. [source] Conductive composites of UHMWPE and ceramics based on the segregated network conceptPOLYMER ENGINEERING & SCIENCE, Issue 1 2000J. Bouchet The manufacturing of composites of ultra high molecular weight polyethylene and ceramics with conductive properties has been investigated. Attention has been focused on the lowering of the amount of filler necessary to achieve low resistivity. Using segregated networks, mixing large polymer particles and submicron metal or conductive ceramic particles may be an interesting route, provided that the processing method enables to generate the desired structures. Because sintering avoids the intimate blending of the components, it is a suitable technique for this aim. The combined effects of temperature, pressure and sintering time have been investigated. The influence of the blending of the solids on the covering of the polyethylene particles before the sintering has also been pointed out. The typical features related to the concept of a segregated network are discussed in connection with the morphologies of the polymer and ceramic particles. The successful application of the reduction of the percolation threshold by a segregated network in conductive composites of polymer and metallic particles is described. [source] Carbon-Supported Ruthenium Nanoparticles Stabilized by Methylated Cyclodextrins: A New Family of Heterogeneous Catalysts for the Gas-Phase Hydrogenation of ArenesCHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2008Audrey Denicourt-Nowicki Dr. Cooperation effects: A novel strategy to obtain heterogeneous catalysts for gas-phase hydrogenation has been developed, based on metallic nanoparticles stabilized by methylated cyclodextrins (CDs) and adsorbed onto charcoal. The CDs appear as multifunctional molecular receptors capable of stabilizing and dispersing the metallic particles on the support and modifying the stereoselectivity through host,guest interactions. 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