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Caractérisation cinétique et structurale de verres sodo-silicatés soumis à un échange ionique au potassium

Abstract : The new industrial boom of the market for mobile applications such as smartphones or tablets requires much research in order to touch-screens design more resistant. The potassium ion exchange process improves the mechanical strength of glass by Na⁺ ions substitution with K⁺ ions, of larger ionic radius. It thus helps to block surface cracks in glass and reduce breakage of the material. This work is devoted to understand the principle of K⁺ diffusion in the silicate structure of different glasses. The parameters: time, temperature and glass composition affect the kinetic of ion exchange process. In the same quenching conditions, the limitation of the composition just to a former network and a mobile ion can improve the diffusion and the penetration ions inside the material. The quenching conditions, temperature and time, act on the kinetic diffusion. They reduce the mobility of the ions through the structure of the silicate material with a change of behaviour above 8h immersion in molten salts. Substitution of Na⁺ by K⁺ ions having different size affect the environment of the sites left vacant by the Na⁺ ions and modifies the silicate structure of the glass. IR spectroscopy allows highlighting the structural modifications of the glass submitted to this ion exchange process. During the introduction of the K⁺ ions inside the glass, the silicate structure is depolymerized and creates no-bridging oxygens. This allows to demonstrate that the ion exchange lead to the mechanical improvement of the glass.
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Valérie Leboeuf. Caractérisation cinétique et structurale de verres sodo-silicatés soumis à un échange ionique au potassium. Science des matériaux [cond-mat.mtrl-sci]. Université d'Orléans, 2015. Français. ⟨NNT : 2015ORLE2041⟩. ⟨tel-01341605⟩

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