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AbstractAbstract
[en] The present work is part of the Fourth Generation Fast Reactors program. One of the key issues is the joining of the SiCf/SiC ceramic matrix composites (CMC) to seal the combustible cladding. At the present time, no chemical composition as a joint is refractive enough to face the expected operating temperatures. The aims of this study are the following: (1) the identification of a joining composition and its associated elaboration process answering the specifications, (2) the validation of a local and fast heating process and (3) the definition of mechanical tests to characterise these joinings. We describe the methodology and the results for joining SiC and SiCf/SiC substrates at solid and liquid state using metallic silicides. Joint integrity and joint strength can be improved by adding small SiC particles to the silicides powders. Chemical reactivity, wettability tests and thermomechanical properties analysis have been carried out on the joints. Cross sections of the assembly were prepared to study the joint/substrate chemical bonding, the cracking and the crack deflection in the vicinity of the interface. Also, one of the challenge consists in using a local heating at a high temperature (around 1800 C) for a short time to avoid the degradation of the composite structure. The assemblies have been then performed in an inductive furnace but in order to prepare the joining technology, trials of local heating have also been investigated with a CO2 laser beam and a microwave generator. Finally, descriptions of the 4-points bending mechanical test used and the associated results are presented. (author)
[fr]
Les composites a matrice ceramique (CMC) SiCf/SiC sont des materiaux envisages pour le gainage du combustible dans les futurs reacteurs a neutrons rapides. Une des problematiques de mise en oeuvre concerne leur assemblage et notamment la fermeture de ces objets. A l'heure actuelle, aucune composition de joint d'assemblage suffisamment refractaire n'est mentionnee dans la litterature. Les objectifs de cette etude sont: (1) la recherche d'un materiau d'assemblage et du procede associe repondant aux contraintes de mise en oeuvre et de fonctionnement, (2) la validation d'un procede 'nuclearisable' de chauffage localise et rapide afin de ne pas degrader le composite lors de l'assemblage et (3) la definition de tests mecaniques pour caracteriser ces assemblages. Apres une etude bibliographique approfondie des systemes d'assemblage potentiels et la selection d'une composition a travers des travaux experimentaux exploratoires par frittage flash, la solution proposee est de realiser un brasage a partir d'une composition mixte de disiliciure metallique (MSi2) et de carbure de silicium (SiC). Le choix du brasage a necessite une etude de mouillabilite et de cinetique d'etalement de la brasure en prenant en compte les aspects reactifs de celle-ci sur le carbure de silicium. Differents procedes de chauffage localise de la brasure tels que le laser CO2, les micro-ondes ou le chauffage inductif haute frequence ont ete testes. La faisabilite de differents procedes d'elaboration du joint a ete montree, notamment par depot physique en phase vapeur (PVD), par projection plasma et par enduction de suspensions de poudres. Un essai de flexion 4-points a egalement ete defini afin d'evaluer la resistance mecanique des assemblagesOriginal Title
Assemblage de composites SiCf/SiC de fine epaisseur: recherche d'une composition de joint et d'un procede associe
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14 Nov 2012; 265 p; [135 refs.]; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS-NKM website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/; Physico-Chimie de la Matiere Condensee
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