Synthèse et caractérisation de borures, carbures et nitrures de M (M=Hf ou Zr) à partir de mélanges de poudres à base de HfCl4 ou MO2 activés mécaniquement : essais préliminaires de frittage de poudres de HfB2

Abstract : In this work, we have studied the synthesis ofborides, carbides and nitrides of zirconium and hafnium, from powders of chlorides and oxides by mechanosynthesis or bail milling. The interest is to synthesize by a new way, Jess complicated than those usually applied, useful compounds for nuclear industry and to increase the value of secondary products of this industry. The compounds have been synthesized in three stages : bail milling, thermal treatment and washing. The reactional mechanisms have been investigated for ail mixtures at every stage. The products of mechanosynthesis have been characterized mainly by X-ray diffraction, thermal analysis, scanning and transmission electronic microscopy, mass and infra-red spectroscopy. The ball milling conditions (duration and amount of reagents) have been optimized to obtain pure products. After thermal treatrnent under flowing neuter atmosphere, the mixtures have been washed by hydrochloric acid and / or alcohol to extract the secondary products of the reaction. The microstructures of products have been characterized. When the bor ides are synthesized from hafnium tetrachloride, according to the composition of original mixture the morphology of single cristals is either facetted grains or nanorods, the diameter of wich is around 100 nm. We have shown the conditions necessary to obtain the nanorods and we have suggested hypotheses to explain their growth mechanism. In the particular case of hafnium borides, their densification by hot pressing bas been investigated.
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_2003_BARRAUD_E.pdf
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https://hal.univ-lorraine.fr/tel-01750085
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Submitted on : Thursday, March 29, 2018 - 12:37:28 PM
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Élodie Barraud. Synthèse et caractérisation de borures, carbures et nitrures de M (M=Hf ou Zr) à partir de mélanges de poudres à base de HfCl4 ou MO2 activés mécaniquement : essais préliminaires de frittage de poudres de HfB2. Autre [cond-mat.other]. Institut National Polytechnique de Lorraine, 2003. Français. ⟨NNT : 2003INPL049N⟩. ⟨tel-01750085⟩

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