Structural Study of SiC Nanoparticles Grown by Inductively Coupled Plasma and Laser Pyrolysis for Nanostructured Ceramic
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0981-JJ06-01
Structural Study of SiC Nanoparticles Grown by Inductively Coupled Plasma and Laser Pyrolysis for Nanostructured Ceramics Elaboration Yann Leconte1,2, Marc Leparoux2, Xavier Portier3, Nathalie Herlin-Boime1, Stephan Siegmann2, Lukas Rohr2, and Cecile Reynaud1 1 DSM/DRECAM/SPAM/LFP URA CNRS 2453, CEA/CNRS, bat. 522, CEA Saclay, gif sur yvette, 91191, France 2 laboratory for materials technology, EMPA, feuerwerkerstrasse 39, Thun, 3602, Switzerland 3 CNRS UMR 6176, SIFCOM - ENSICAEN, 6 boulevard du maréchal Juin, caen, 14000, France
ABSTRACT Refractory carbide nanostructured ceramics as SiC constitute interesting materials for high temperature applications and particularly for fourth generation nuclear plants. To elaborate such nanomaterials, weighable amounts of SiC nanopowders have to be synthesized first with an accurate control of the grain size and stoichiometry. The inductively coupled plasma and the laser pyrolysis techniques, respectively developed at EMPA Thun and CEA Saclay, allow meeting these requirements. Both techniques are able to produce dozens of grams per hour of silicon carbide nanopowders. The particle size can be adjusted down to around 20 nm for the plasma synthesis and even down to 5-10 nm for the laser pyrolysis. The stoichiometry Si/C can be tuned by the addition of methane into the plasma and acetylene for the laser process. INTRODUCTION Refractory carbide ceramics as SiC appear as promising materials for high temperature applications. When these ceramics become nanostructured, some of their mechanical properties are improved and some typical drawbacks (brittleness, low ductility) of conventional ceramics can be overcome. Different studies have already demonstrated increased hardness [1], improved resistance to plasma erosion or to thermal shocks [2,3] in nanomaterials. Moreover, the reinforcement of composites by nanometric components has already shown enhanced mechanical properties. The high grains boundary density that can be found in nanomaterials could also improve their resistance to irradiation [4]. Over the last twenty years, new technologies have been developed to synthesize nanopowders. Among these technologies, we report here the synthesis of SiC nanopowders by inductively coupled plasma (ICP) and laser pyrolysis. Different approaches can be used concerning the precursors and the way to create the plasma, and the method developed at Empa Thun uses the evaporation of a micrometric SiC powder as a precursor within a RF thermal plasma and subsequently the rapid condensation of the gaseous phase by Ar. The process parameters have already been described and simulated by a group in Empa Thun [5,6]. Concerning the laser pyrolysis technique, it was created in the 80’s in the US [7], and then developed at CEA Saclay [8]. This synthesis method uses the decomposition of a gaseous mixture (silane + acetylene) by a powerful CO2 laser, leading to the nucleation and growth of nanoparticles in the vapor phase.
EXPERIMENT The inductively coupled plasma (ICP) reactor developed at Em
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