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Multiscale Copper-uDiamond Nanostructured Composites
Nunes, D.; Livramento, Vanessa; Fernandes, H.; Silva, C.; Shohoji, Nobumitsu; Correia, J. Brito; Carvalho, P. A.Nanostructured copper-diamond composites can be tailored for thermal management applications at high temperature. A novel approach based on multiscale diamond dispersions is proposed for the production of this type of materials: a Cu-nDiamond composite produced by high-energy milling is used as a nanostructured matrix for further dispersion of micrometer sized diamond. The former offers strength and microstruct...
Synthesising carbo-nitrides of some d-group transition metals using a solar fur...
Shohoji, Nobumitsu; Oliveira, F. A. Costa; Rosa, Luís Guerra; Fernandes, Jorge Cruz; Magalhães, Teresa; Coelho, Manuel Caldeira; Rodriguez, JoséCarbo-nitride synthesis was undertaken using a solar furnace at PSA in flowing N2/Ar gas mixture under total pressure 1 atm and processing temperature T = 1600ºC for some d-group transition elements (Ti; Zr, V, Nb, Mo, W) starting from 1.5G/M (graphite/metal powder mixture with mole ratio 1.5:1) compact to ensure co-presence of free carbon with the reaction product. Clear X-ray diffraction (XRD) evidence of for...
Synthesizing higher nitride of molybdenum (Mo) and iron (Fe) in ammonia (NH3) g...
Shohoji, Nobumitsu; Oliveira, F. A. Costa; Fernandes, Jorge Cruz; Rosa, Luís Guerra; Rodriguez, José; Canadas, Immaculada; Ramos, CarlosFlowing gaseous ammonia NH3 with suppressed extent of dissociation (un-cracked NH3) is acknowledged to function as a powerful nitriding medium to realize formation of metal nitride MNx with considerably high N/M ratio x that cannot be achieved through reaction of M with N2 gas. For example, mono-nitride d-MoN of Mo and e-FeNx phase of Fe with x = 0.33 ˜ 0.50 (i. e. hypo-stoichiometric sub-nitride e-Fe2N) were r...
Statistical Thermodynamic Analysis for Isothermal Hydrogenation Performances of...
Shohoji, NobumitsuIsothermal hydrogenation performances of intermetallic Mg2-yPryNi4 alloys with y = 0.6, 0.8 and 1.0 reported by Terashita et al.were analyzed on the basis of statistical thermodynamics under a simplifyinga priori assumption of constant nearest neighbourH-H interactionE(H-H) in a given phase at arbitrary T aiming at characterizing basic aspects of state of H atoms in the interstitial sites in H-storage alloy. To...
Chemical Activities, a(H) and a(X), of Constituents in H2X Type Gas Molecules (...
Shohoji, NobumitsuChemical activities, a(X) and a(H), of constituents, X and H, in H2X type gas molecules (X = S or O) were evaluated as functions of temperature T and extent α of dissociation adapting a thermodynamic analysis procedure developed by Katsura for interpreting enhanced a(N) and a(H) in NH3 gas molecules with suppressed α by flowing. Present analysis results showed that both H2S and H2O gas molecules are chemically ...
Hydrogen absorption in epitaxial bcc V (001) thin films analysed by statistical...
Shohoji, NobumitsuAndersson, Aits and Hjörvarsson of Uppsala Universitymeasured hydrogen uptake in epitaxial bcc (body centred cubic) vanadium (V) (001) thin films of thickness, 50 nm and 100 nm, over temperature range between 443 K and 513 K. The reported equilibriumpressure–temperature–composition (P–T–C) relationships for the epitaxial bcc V (001) thin films showed appreciable extent of enhancement ofH solubility comparedwith...
Heterogeneity along the Height in Disc Specimens of Graphite/Tungsten Powder Mi...
Shohoji, Nobumitsu; Magalhães, Teresa; Oliveira, F. A. Costa; Rosa, Luís Guerra; Fernandes, Jorge Cruz; Rodriguez, José; Canadas, ImmaculadaCompositional heterogeneity along the thickness of compacted disc specimens of graphite/tungsten powder mixtures with substoichiometric carbon atom ratios (0.35, 0.50 and 1.00) heated by concentrated solar beam to 1600 C was characterised by X-ray diffraction. Top surface of any examined test piece was consisted purely of mono-carbide WC while the bottom surface showed different constitution depending on the ne...
Production of Cu/Diamond composites for first-wall heat sinks
Nunes, D.; Correia, J. Brito; Carvalho, P. A.; Shohoji, Nobumitsu; Silva, C.; Fernandes, H.; Alves, L. C.; Hanada, K.; Osawa, E.Due to their suitable thermal conductivity and strength copper-based materials have been considered appropriate heat sinks for first wall panels in nuclear fusion devices. However, increased thermal conductivity and mechanical strength are demanded and the concept of property tailoring involved in the design of metal matrix composites advocates for the potential of nanodiamond dispersions in copper. Copper-nano...
Two-step processing of hydrogen storage FeTi Alloys: influence on reaction temp...
Rangel, C. M.; Livramento, Vanessa; Correia, J. Brito; Shohoji, NobumitsuIn the present work, nanostructured FeTi powders were produced by mechanical alloying, avoiding the unfavorable agglomeration problem by using a low energy milling (e.g. 300 rpm) of pure metallic constituents, Fe and Ti, followed by subsequent heat treatment at 800ºC. A major achievement of this research was to show that by modulating the milling intensity and total milling time, the high temperature synthesis ...
Mechanical properties of dense cordierite discs sintered by solar radiation hea...
Oliveira, F. A. Costa; Shohoji, Nobumitsu; Martinez, Diego; Fernandes, Jorge Cruz; Rodriguez, José; Rosa, Luís Guerra; Canadas, ImmaculadaConsolidation of cordierite disc specimens was undertaken under concentrated solar beam in a solar furnace at PSA (Plataforma Solar de Almerıá). Satisfactory extent of densification was achieved by the present solar-sintering experiment. The mechanical properties measured for the solar-sintered cordierite test pieces were; density ¼ 2:45 0:02 g/cm3, Vickers microhardness HV ¼ 7:31 0:29 GPa, Young’s modulu...
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