Sintering of Industrial Mullites in the Presence of Magnesia as a Sintering Aid |
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Authors: | Laura Montanaro Christophe Perrot Claude Esnouf Gilbert Thollet Gilbert Fantozzi Alfredo Negro |
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Affiliation: | Department of Materials Science and Chemical Engineering-FERMAP-Politecnico of Torino, 10129 Torino, Italy, and GEMPPM, INSA de Lyon, 69621 Villeurbanne, France |
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Abstract: | The sinterability of two industrial mullite powders, in the presence of MgO as a sintering aid, was investigated. A glassy phase, which was generated during preparation, was present in both powders; this glassy phase had a strong influence on sintering, depending on its content, composition, and spatial distribution. MgO promoted sintering in the presence of a liquid phase, both in the as-received materials and in samples washed with HF, in which most of the pre-existing glassy phase was eliminated. Investigations using transmission electron microscopy, coupled with energy-dispersive spectroscopy, as well as dilatometric measurements and X-ray diffraction data, on washed and unwashed materials and on quenched and slow-cooled samples allowed a better understanding of the influence of MgO and the glassy phase on the sintering behavior and the formation of new phases. Most of the phases, in fact, can be explained by using the MgO–Al2O3–SiO2 phase diagram, even in such complex systems. |
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Keywords: | sintering mullite magnesium oxide |
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