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Mécanismes et cinétiques d'oxydation de matériaux ultraréfractaires sous conditions extrêmes

Abstract : Ultra-High Temperature Ceramics (UHTC) are promising materials for applications in extreme environments such as prominent parts of atmospheric re-entry vehicles or the combustion chambers of aeronautic engines. The understanding of oxidation mechanisms at high temperature is of great interest, because reactions in oxidizing atmosphere strongly shorten their lifetime. ZrB2-SiC, HfB2-SiC and HfB2-SiC-Y2O3 materials have been subjected to controlled water vapor-containing environments for different durations and temperatures (up to 2400°C). The microstructures developed by the oxidized materials have been described, and oxidation mechanisms and kinetics governing their behavior have been analyzed. The importance of the stability and nature of the vitreous phase formed during the oxidation has been emphasized. In order to complement these microstructural analyses, tests using Light-Induced Fluorescence (LIF) have been performed, allowing us to finely understand the dynamics of the vitreous phase during oxidation thanks to the in situ detection of the BO2 molecule. Finally, a modelling of the growth of oxidized layers on a single-phased material has been performed.
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https://tel.archives-ouvertes.fr/tel-02415214
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  • HAL Id : tel-02415214, version 2

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Vincent Guérineau. Mécanismes et cinétiques d'oxydation de matériaux ultraréfractaires sous conditions extrêmes. Matériaux. Université Pierre et Marie Curie - Paris VI, 2017. Français. ⟨NNT : 2017PA066646⟩. ⟨tel-02415214v2⟩

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