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Effets du zirconium, du manganèse et du titane sur la thermoluminescence et la réactivité de l'alumine-alpha

Abstract : To obtain ceramic materials with controlled properties, mineral additions in small quantity are generally used.
These additions make it possible to support the densification, to control the phenomenon of grain growth, or to modify the mechanical, physical or optical properties.
This study aims to characterize and model the action of certain dopants at the same time on the reactivity and the microstructure, and on the optical properties of alpha-alumina.
We showed that low temperature thermoluminescence (TL) after an UV excitation is an excellent technique making it possible to detect the presence of the zirconia tetragonal phase stabilized by alumina. Low temperature TL of the alumina-manganese composites is influenced by an 675,5-679 nm emission. Several assumptions on the recombination center being in charge of this emission were advanced: Mn4+, Cr3+ present in an other matrix than alumina, or at the same time Mn4+ (at 675,5 nm) and Cr3+ in another matrix (at 679 nm). Low temperature TL of the alumina-titania composites is influenced by the Ti3+ ion acting as recombination center and traps center. Ambient temperature TL of the alumina-titania composites is influenced by the Ti4+ ion acting as recombination center and traps center. This influence of Ti4+ can be observed on the D' peak with a double band of blue-green emission ascribable to the Ti4+ center and the (Ti4+-VAl') aggregate.
We highlighted for the alumina-zirconia composites, that a heat treatment of the mixture will be preferable for the sintering than a treatment of oxides before mixture. A liquid phase during sintering in presence of manganese allows to support the densification of alumina. One notes it by the presence of a second peak on the derived curves of dilatometry. We could also highlight the presence of segregation of manganese at the grain boundaries with the alumina impurities: iron, calcium. The presence of titanium supports the densification, as well as the the grain growth. We could highlight the segregation at the grain boundaries of TiO2 excess beyond the limit of solubility, as well as the presence of the secondary phase Al2TiO5 on the surface of the samples.
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Submitted on : Tuesday, August 8, 2006 - 5:39:43 PM
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  • HAL Id : tel-00089012, version 1

Citation

Christian Sallé. Effets du zirconium, du manganèse et du titane sur la thermoluminescence et la réactivité de l'alumine-alpha. Génie des procédés. Ecole Nationale Supérieure des Mines de Saint-Etienne, 2003. Français. ⟨tel-00089012⟩

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