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Hydrogen Flux (hydrogen + flux)
Selected AbstractsNanocrystalline non-planar carbons: Growth of carbon nanotubes and curled nanostructuresCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005S. Orlanducci Abstract We present a variety of non-planar graphitic nanostructures selectively generated in a modified Hot-Filament Chemical Vapour Deposition (HF-CVD) apparatus, using purpose-synthesized amorphous carbon nanoparticles or graphite powders as solid state precursor. The employed methodologies enable to successfully synthesize homogeneous and well organized deposits of single- and multi-walled carbon nanotubes, onion-like nanostructures, and nanotube bundles coated by nano-sized diamond grains. Variations in the morphological aspect of such non-planar graphite-based nanostructures are observed changing the experimental conditions: the solid state reactants, the filament and substrate temperatures, the catalyst concentration, and the atomic hydrogen flux over the substrate play key roles in the phenomenon. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Design of Experiments (DOE) for the Optimization of Titania,hydroxyapatite Functionally Graded CoatingsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2009Valeria Cannillo Titania,hydroxyapatite functionally graded coatings were deposited on titanium alloy substrates by plasma spraying. Because it was necessary to spray together the titania and the hydroxyapatite powders to obtain the graded system, the first target of the present study was to optimize the process parameters in order to obtain a high-quality coating. A 23 Design of Experiments was applied to define the optimal values of plasma torch power, hydrogen flux, and spraying distance. This defined set of parameters (38 kW, 5 SLPM, and 90 mm, respectively) was used to spray the most promising graded coating, which was characterized and postheat treated. [source] Pd membranes formed by electroless plating with osmosis: H2 permeation studiesAICHE JOURNAL, Issue 2 2002Razima S. Souleimanova The synthesis of fully dense Pd-Vycor glass composite membranes by electroless plating with or without osmosis is reported. Use of osmotic flux allows one to rapidly form thin (a few microns), fully dense palladium films, which have submicron size microstructure. These features significantly enhance hydrogen permeability as compared to the conventional method. By accounting for resistance of the porous support, it is confirmed that for membranes prepared by the same technique, with gradually changing microstructural characteristics, those with smaller palladium crystallites exhibit larger hydrogen flux. Pd-stainless steel composite membranes were also prepared using electroless plating, either with or without osmosis. Membranes synthesized using osmosis exhibit superior thermal stability. [source] Fabrication of Thin-Film SrCe0.9Eu0.1O3,, Hydrogen Separation Membranes on Ni,SrCeO3 Porous Tubular SupportsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Heesung Yoon SrCe0.9Eu0.1O3,, thin-film (,30 ,m) tubular hydrogen separation membranes were developed in order to obtain high hydrogen fluxes. Fifteen centimeters long, one end closed, NiO,SrCeO3 tubular supports were fabricated by tape casting, followed by rolling the green tape on a circular rod. SrCe0.9Eu0.1O3,, powders were prepared by the citrate process and coated on partially sintered NiO,SrCeO3 tubular supports. Leakage-free hydrogen membrane cells were obtained by adjusting the presintering and final sintering temperatures to reduce the difference of linear shrinkage rates between SrCe0.9Eu0.1O3,, thin films and NiO,SrCeO3 supports. A hydrogen flux of 2.2 cm3/min was obtained for the SrCe0.9Eu0.1O3,, on Ni,SrCeO3 tubular hydrogen separation membranes at 900°C using 25% H2 balanced with Ar and 3% H2O as the feed gas and He as the sweep gas. Thus, a 40% single pass yield of pure H2 was achieved with this membrane. [source] | ||||||||||