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Frittage et évolution microstructurale de céramiques de type oxyde

Abstract : The sinterability and the microstructural development of various zirconia powders stabilized with yttrium oxide and alumina are studied. The zirconia powders of average specific surface area obtained industrially by vapor phase hydrolysis of zirconium tetrachloride, sintered at an optimum temperature (1300-1350 ° C.), lead to dense me terials containing very little monoclinic phase. The poor sinterability of the zirconia powders, produced by pyrolysis of mixed acetates of zirconium and yttrium, is related to their strong agglomeration. The reaction zirconia synthesis in molten salt media produces very fine and densifiable powders. Fine particle size, low impurity content, high green density and the addition of magnesium oxide favor the densification of alumina powders ex-alum. These parameters also contribute to obtaining a sintered material having a fine and homogeneous microstructure. At the end of the sintering of ex-alum aluminas, the characteristics (density, microstructure) of the samples do not depend significantly on the content of transition phases (gamma alumina) of the powders. In the absence of exaggerated grain magnification, the median value of the number distribution of grain size of a sintered alumina is correlated with the density of the sample. During the final stage of the sintering of the Bayer aluminas, the exaggerated magnification of the grains develops. For the finest powders, this magnification is accompanied by a drop in density.
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https://hal.archives-ouvertes.fr/tel-01774116
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  • HAL Id : tel-01774116, version 1

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M. Descemond. Frittage et évolution microstructurale de céramiques de type oxyde. Sciences de l'ingénieur [physics]. Ecole nationale supérieure des Mines de Saint-Etienne, 1991. Français. ⟨tel-01774116⟩

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