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Articles dans des revues avec comité de lecture |
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| Domaine : |
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| Titre : |
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Influence of limestone grain size on glass homogeneity |
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| Auteur(s) : |
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M.H. Chopinet 1, Emmanuelle Gouillart ( ) 1, Michael Toplis 2, Sophie Papin 3 |
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| Laboratoire : |
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| Résumé : |
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The lack of homogeneity in a glass is characterized by the occurrence of layers of different chemical compositions and densities. When starting materials relevant for the synthesis of soda-lime silicate glasses are melted in a crucible, silica- and calcium-enrichments are observed at the top and at the bottom of the melt respectively. This behaviour may be due to the occurrence of several reaction pathways. In this respect, an interesting observation is that the grain size of limestone is found to be an important parameter influencing the level of glass homogeneity. The reasons for this have been studied here using systematic differential thermal analysis and thermogravimetric analysis. The experiments showed that, in presence of limestone of small grain size (< 200 micrometers), sodium carbonate disappears before the temperature at which it is observed to interact with silica in the CaO - free system. We infer that this is most probably due to production of a mixed carbonate liquid, which subsequently reacts with silica to spontaneously yield a homogeneous silicate melt. A characteristic of this probable mixed carbonate (assumed to be close to the composition CaNa2(CO3)2) is its density of 2.54g/cm3, close to that of the silicates and of silica itself. On the contrary, coarse limestone decomposes to CaO (and CO2), which is slowly incorporated in the sodium silicate liquid formed when sodium carbonate interacts with silica. The much higher density of CaO (3.35 g/cm3) and of calcium silicates could explain the tendency for CaO concentrations to be greatest towards the base of melting crucibles. |
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Langue du texte
intégral : |
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Anglais |
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Date de production,
écriture : |
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10/11/2009 |
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| Journal : |
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| Audience : |
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internationale |
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| Date de publication : |
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01/06/2010 |
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| Volume : |
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51 |
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| Numéro : |
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3 |
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| Page, identifiant, ... : |
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116 |
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| Mots Clés : |
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glass melting – glass batch – limestone |
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