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Papers by Eric Bouchard
La nature chimique de la liaison fibre-matrice dans les composites carbone-carbone, a ete etudiee... more La nature chimique de la liaison fibre-matrice dans les composites carbone-carbone, a ete etudiee en deux etapes. - la premiere est la caracterisation par microscopie a effet tunnel de la surface des fibres de carbone de l'echelle micrometrique a l'echelle atomique. L'orientation des feuillets graphitiques, la porosite et la rugosite de surface semblent liees a la nature du precurseur (pan, brais ou rayonne). La graphitation apparait plus facile en surface que celle supposee pour le coeur de la fibre. Elle tend a diminuer la rugosite de la surface et a accroitre les longueurs de coherence intraplanaires. Enfin le traitement d'oxydation anodique commercial augmente globalement la rugosite de la surface, cree certaines piqures et enleve certaines ecailles de la surface. - la seconde concerne la nucleation et la croissance des depots de pyrocarbone sur du hopg. Les observations stm montrent que : 1 o les depots laminaires lisses croissent de facon radiale avec un angle ...
Chemical Vapor Deposition, 2001
The CVD of carbon materials is a complex process leading to different types of pyrocarbons, in pa... more The CVD of carbon materials is a complex process leading to different types of pyrocarbons, in particular rough laminar (RL) and smooth laminar (SL) microstructures. In the current study, we examined the behavior of the gas-solid interface during the nucleation and growth processes of pyrocarbons. Using a classical, isothermal-isobaric CVD technique, we prepared deposits on ideal pyrographite surfaces. In order to investigate the first deposition steps, we studied short deposition times for various residence times giving rise to either RL or SL pyrocarbons. Using scanning tunneling microscopy (STM) on different scales, we observed these deposits and measured the associated contact angles. The two typical microstructures, SL and RL, were found to be related to different types of heterogeneous nucleation. The controlled morphological change can be interpreted as a sort of wetting transition of the pyrographite surface, associated with the surface chemical reactions. Indeed we have clarified the role of interfacial interactions in the origin of these different classes of pyrocarbon deposits.
La nature chimique de la liaison fibre-matrice dans les composites carbone-carbone, a ete etudiee... more La nature chimique de la liaison fibre-matrice dans les composites carbone-carbone, a ete etudiee en deux etapes. - la premiere est la caracterisation par microscopie a effet tunnel de la surface des fibres de carbone de l'echelle micrometrique a l'echelle atomique. L'orientation des feuillets graphitiques, la porosite et la rugosite de surface semblent liees a la nature du precurseur (pan, brais ou rayonne). La graphitation apparait plus facile en surface que celle supposee pour le coeur de la fibre. Elle tend a diminuer la rugosite de la surface et a accroitre les longueurs de coherence intraplanaires. Enfin le traitement d'oxydation anodique commercial augmente globalement la rugosite de la surface, cree certaines piqures et enleve certaines ecailles de la surface. - la seconde concerne la nucleation et la croissance des depots de pyrocarbone sur du hopg. Les observations stm montrent que : 1 o les depots laminaires lisses croissent de facon radiale avec un angle ...
Chemical Vapor Deposition, 2001
The CVD of carbon materials is a complex process leading to different types of pyrocarbons, in pa... more The CVD of carbon materials is a complex process leading to different types of pyrocarbons, in particular rough laminar (RL) and smooth laminar (SL) microstructures. In the current study, we examined the behavior of the gas-solid interface during the nucleation and growth processes of pyrocarbons. Using a classical, isothermal-isobaric CVD technique, we prepared deposits on ideal pyrographite surfaces. In order to investigate the first deposition steps, we studied short deposition times for various residence times giving rise to either RL or SL pyrocarbons. Using scanning tunneling microscopy (STM) on different scales, we observed these deposits and measured the associated contact angles. The two typical microstructures, SL and RL, were found to be related to different types of heterogeneous nucleation. The controlled morphological change can be interpreted as a sort of wetting transition of the pyrographite surface, associated with the surface chemical reactions. Indeed we have clarified the role of interfacial interactions in the origin of these different classes of pyrocarbon deposits.