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ETUDE DE NOUVELLES CERAMIQUES POUR BARRIERE THERMIQUE

Abstract : The topic of this work is the search for news ceramics able to operate at higher temperature than yttria partially stabilised zirconia, presently the most widely used ceramic as insulating thermal barrier coating in aeronautical and land-based gas turbines. The analysis of several criteria to be met by such ceramic led to the selection of perovskites. Calculations of thermal conductivity based on a molecular dynamic approach, have been performed and a complex perovskite, BaMg1/3Ta2/3O3 (BMT), has been selected. A solid state approach has been developed to manufacture this oxide as well as yttria fully stabilised zirconia as a reference. Their microstructure has been studied by XRD, SEM, EDS and porosimetry, their thermal conductivity and thermal expansion coefficient have been determined up to 1200°C, both experimentally (laser flash and dilatometry) and numerically (molecular dynamics). Lastly, grain boundaries grooving experiments by AFM have been performed to provide information, in particular surface diffusion coefficients, to assess their respective sintering resistance. It comes out from this study that perovskite BMT has a whole of interesting properties to constitute a thermal barrier coating: phase stability, thermal conductivity at 1200°C in the same order of yttria zirconia, high thermal expansion coefficient. But sublimation phenomena are likely to disturb the stability of coatings at very high temperatures.
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  • HAL Id : tel-00809130, version 1

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Marie-Anne Prevost. ETUDE DE NOUVELLES CERAMIQUES POUR BARRIERE THERMIQUE. Matériaux. Université Pierre et Marie Curie - Paris VI, 2007. Français. ⟨NNT : 2007PA066495⟩. ⟨tel-00809130⟩

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