Effect of Heating Rate on Phase and Microstructural Evolution During Pressureless Sintering of a Nanostructured Transition Alumina |
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Authors: | Paola Palmero Mariangela Lombardi Laura Montanaro Mirella Azar Jerome Chevalier Vincent Garnier Gilbert Fantozzi |
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Affiliation: | Department DISMIC-Politecnico of Torino, INSTM–R.U., PoliTO—LINCE Lab., Corso Duca degli Abruzzi, 24-10129 Torino, Italy; Universitéde Lyon, INSA-Lyon, MATEIS, CNRS UMR 5510, 20 Av.A. Einstein, F-69621Villeurbanne, France |
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Abstract: | Deagglomeration of a nanocrystalline transition alumina performed using different techniques was first demonstrated to be active in the achievement of a better powder compaction ability under uniaxial pressing and consequently in the development of a highly dense and homogeneous microstructure during pressureless sintering. A major effect, however, was associated to the heating rate chosen during the densification cycle. In fact, the influence of different heating rates (10°C/min or 1°C/min) on phase and microstructural evolution during sintering was investigated in depth on the above best green bodies. A low-rate thermal cycle leads to a significant reduction of the α-Al2O3 crystallization temperature and promotes a more effective particle rearrangement during phase transformation. As a consequence, in the low-rate treated material, it was possible to avoid the development of a vermicular structure as usually expected during the densification of a transition alumina and to yield a more homogenously fired microstructure. |
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