Contribution à la compréhension du procédé de spray pyrolyse par une double approche modélisation/expérience

Abstract : Multielement ceramic powders in the Si/C/N system could be obtained by spray pyrolysis process. Synthesis parameters and their effect on powder chemical composition and morphology have been already studied. Nevertheless, the mechanisms of precursor decomposition and gas phase species recombination that take place in the reaction zone are still unknown. The aim of this study is the comprehension of the process, from the aerosol generation to the solid powders formation mechanisms. The shadowgraphy technique was used to characterize the spray, and coupled with the implementation of a numerical model of droplets transport and treatment through the device allowed to identify bimodal size distributions at the furnace entrance. This double approach let confirm the effect of physical and hydrodynamic phenomenon in drop size evolution. The introduction of a bimodal distribution into the pyrolysis furnace allows to consider a precursor decomposition mechanism in two steps, depending on the drop sizes. This hypothesis combined to the study of precursor decomposition at high temperature led to the proposal of powder formation mechanisms in which their chemical composition varies with the synthesis atmosphere.
Keywords : Spray pyrolysis
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Theses
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Mariana Munoz Hoyos. Contribution à la compréhension du procédé de spray pyrolyse par une double approche modélisation/expérience. Matériaux. Université de Limoges, 2017. Français. ⟨NNT : 2017LIMO0081⟩. ⟨tel-01721778⟩

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