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Spark Plasma Sintering Behavior of Pure Aluminum Depending on Various Sintering Temperatures
권한상,박대훈,박용하,Jean François Silvain,Akira Kawasaki,박용호 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.1
We have successfully fabricated high-density pure aluminum (Al) bulk by means of a spark-plasma-sintering (SPS) process. The relative density of Al was enhanced as the sintering temperature of the SPS process increased. During the SPS process for pure Al power, the Al oxide layer on the surface of the Al particle was partially broken by the microplasma and applied pressure. The microstructures of the spark-plasma-sintered compacts obtained at various temperatures were observed by optical microscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. We believe that the pinning effect,rapid heating cycle, and applied pressure played an important role in restraining the particle growth despite the increase in sintering temperature. It is feasible that the employed SPS process could be very useful to achieve fully densified Al compact.
권한상,Marc Leparoux,Jean-Marc Heintz,Jean-François Silvain,Akira Kawasaki 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.5
We have successfully fabricated highly densified aluminum (Al)-diamond composite materials by a simple hot press method. The thermal conductivity of the Al-diamond composite materials was measured. These materials had different types, sizes and fractions of diamond. These obtained values were discussed based on theoretically calculated values. The thermal conductivity of the composite materials, measured by Laser-Flash method, was found to have slightly increased compared to that of pure bulk Al. The obtained microstructures of the composite materials showed a lot of cleavage existing in the interface between the Al matrix and the diamond particles, which led to the low increment of the thermal conductivity. Moreover, Al-diamond bulk materials with different sintering temperatures in solid state, liquid phase, and transient region between solid and liquid of Al, have been synthesized.
Control of Mechanical Properties of Functionally Graded Dual-Nanoparticle-Reinforced Composites
Kwon, Han Sang,Park, Je Hong,Kim, Kwon Hoo,Leparoux, Marc,Silvain, Jean Francois,Kawasaki, Akira Trans Tech Publications, Ltd. 2018 Materials science forum Vol.941 No.-
<P>Functionally graded aluminium (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nSiC) or nanodiamond (nD) were fabricated using a powder-metallurgical route. The nSiC and nD were not only used as a reinforcement but also as an active solid mixing agent for dispersing the CNT in the Al powder. Dual-nanoparticle-reinforced functionally graded multiple-layered composites were found to exhibit different mechanical characteristics. In particular, the hardnesses of the CNT-and nSiC-reinforced composites were dramatically increased, being up to eight times greater (330 HV) than that of bulk pure Al. In the case of the combination of the CNT and nD nanoparticles, the reinforced Al matrix composites exhibited the highest flexural strength (about 760 MPa). This functionally graded dual-nanoparticle approach could also be applied to other nanoreinforced systems, such as ceramics or complex hybrid-matrix materials. Keywords: Carbon nanotubes (CNT), nanosilicon carbide (nSiC), nanodiamond (nD), functionally graded materials (FGM), Powder metallurgy</P>
Nabil Chamroune,Florence Delange,Nathalie Caillault,Fabrice Morvan,Yongfeng Lu,Akira Kawasaki,Jean‑François Silvain 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.2
Aluminum (Al) matrix composite materials reinforced with graphite fakes (GF) and pitch-based carbon fbers (CF) werefabricated by solid–liquid phase sintering with a small amount of Aluminum–Silicon eutectic alloy (Al-12 wt%Si). Theamount of Al–Si is optimized for a carbon content of 50 vol% in order to achieve, in the plane of GF reinforcement, a higherthermal conductivity (TC) and a lower coefcient of thermal expansion (CTE) compared to identical composite material fabricated by conventional powder metallurgy route. Al/(GF+CF) composite materials were characterized by scanning electronmicroscopy (SEM), energy-dispersive X-ray microscopy and X-ray tomography in order to highlight the distribution of theAl–Si liquid phase and the formation of a carbon network in the aluminum matrix. A small amount of CF allows to controlthe through-plane CTE without afecting signifcantly the in-plane TC of the Al-C composites. The (GF+CF) mixture andthe solid–liquid phase sintering allow to achieve a TC of 410 W/m K (in-plane direction) and a CTE of 2.4×10−6/K (troughplane direction), which is, for example, applicable for lightweight heat sink material.
F. J. Muller,Q. Rome,M. Arca,G. Arnold,M. Barbet-Massin,F. Jiguet,F. Mougel,A. Perrard,J-F. Silvain,C. Villemant 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.10
The highabundance and impact on honeybees of the Asian hornet Vespa velutina var. nigrithorax have caused great concern among European public authorities and beekeepers. The species was reported for the first time in France in 2005 and spread out across 66 European districts (ca. 360 000 km 2 ) within 7 years (INPN, 2012; Rome et al., 2013). Its arrival was reported in 2010 in Northern Spain, in 2011 in Portugal and Belgium and in 2013 in Italy. Its wider expansion in Europe is soon to be expected. We discuss here the advances of the collaborative research project initiated in 2008 in France. 1. The potential invasion risk of the species was assessed using modeling tools of climatic suitability (Villemant et al., 2011, Barbet-Massin et al., 2013). Interestingly, the potential distribution of V. v. nigrithorax matches the current distribution of another invasive social wasp, the German yellow jacket, Vespula germanica (Beggs et al., 2011). 2. Apartfrom reported damages on hives, little is known on the biology of V. velutina throughout its native Asian range. In the invaded range, the impact of V. v. nigrithorax on the diversity and biomass of the invertebrate fauna is under study. Preliminary results reported a diversified diet varying among seasons and habitat types. 3. The genetic variability between individuals of V. v. nigrithorax from France and Asia was assessed in order to describe the history of its invasion. The analysis has evidenced a low variability among the invasive population, which indicates a single introduction of one or more queens. The sampling of specimens in France and in the area of origin has been extended to confirm this hypothesis and the most probable area of origin (Arca, 2012). Given the potential economic and biological impact of V. v. nigrithorax, a better understanding of its invasion dynamics is necessary to predict regions at risk, hence to help with planning dedicated control measures, a prerequisite for replacing the reactive nature of current solutions with a proactive, predictive approach.