The high temperature reaction of ammonia with carbon and SiC–C ceramics
In: Journal of the European Ceramic Society, Jg. 41 (2021), S. 136-147
Online
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Zugriff:
International audience; This contribution aimed at developing a treatment under ammonia in order to eliminate free carbon from the surface of SiC-based fine ceramics like fibers or coatings. The reaction of NH3 with graphitic and non-graphitic carbon was first investigated through kinetic measurements, in situ gas phase analysis and physicochemical investigations of the solid. The carbon etching rate is controlled by heterogeneous reactions involving active sites arising from bulk structural defects and the formation of HCN. A selection of SiC-based fibers and coatings with various carbon contents and (micro)structures was treated in ammonia in favorable conditions. The analyses of the tested SiC-C specimens revealed a reduction of the free carbon content and, simultaneously, a nitridation of the initial Si-C-(O) continuum over a reaction layer. The growth rate, composition and the volume change of this layer vary with the initial microstructure. The ammonia treatment is able to restore the adhesion of carbon-contaminated surfaces.
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The high temperature reaction of ammonia with carbon and SiC–C ceramics
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Autor/in / Beteiligte Person: | Chollon, Georges ; Admin, Oskar ; Laboratoire des Composites Thermostructuraux (LCTS) ; Université de Bordeaux (UB)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Snecma-SAFRAN group-Centre National de la Recherche Scientifique (CNRS) ; Centre National de la Recherche Scientifique (CNRS)-Snecma-SAFRAN group-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA) |
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Zeitschrift: | Journal of the European Ceramic Society, Jg. 41 (2021), S. 136-147 |
Veröffentlichung: | Elsevier BV, 2021 |
Medientyp: | unknown |
ISSN: | 0955-2219 (print) |
DOI: | 10.1016/j.jeurceramsoc.2020.08.066 |
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