Role of the dispersion route on the phase transformation of a nano-crystalline transition alumina |
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Authors: | Paola Palmero Barbara Bonelli Fernando Lomello Edoardo Garrone Laura Montanaro |
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Institution: | (1) Politecnico di Torino, Department of Materials Science and Chemical Engineering, INSTM—R.U. PoliTO—LINCE Lab, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy;(2) Politecnico di Torino, Department of Materials Science and Chemical Engineering, INSTM—R.U. PoliTO, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy |
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Abstract: | De-agglomeration of a nanocrystalline transition alumina powder was performed in distilled water at its natural pH under magnetic
stirring for 170 h or by ball milling for 3 h. Gibbsite appeared near transition aluminas in the magnetic stirred sample.
In addition, a relevant lowering of the α-Al2O3 crystallization temperature was observed in the dispersed materials with respect to the as-received powder. However, the
activation energy of the above transformation, determined by the Kissinger method, was in any case about 480–500 kJ/mol and
unaffected by the dispersion route. On the contrary, it was reduced of about 10% in α-alumina seeded samples, obtained by
flash plunging the powders at 1,290 °C for 10 min. |
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