Aluminum Titanate Formation by Solid-State Reaction of Coarse Al2O3 and TiO2 Powders |
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Authors: | B FREUDENBERG A MOCELLIN |
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Affiliation: | Laboratoire de Céramique, Ecole Polytechnique Fédérale de Lausanne, CH-1007 Lausanne, Switzerland |
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Abstract: | Reaction kinetics in a coarse equimolar powder mixture were slow enough to allow for the different stages to be identified, notably in the lower and higher temperature ranges, respectively. In the former ( T ≤ 1600 K), Al2TiO5 nucleation was hindered by the strain energy contribution to the overall driving force. The setting up of metastable layer sequences Al2TiO5/TiO2/Al2O3 was found to occur generally during subsequent growth. The high Al mobility in the TiO2 provided a rapid aluminum transport from the metastable Al2O3/TiO2 interface to the TiO2/Al2TiO5 front. At temperatures above ~1700 K the Al2O3/TiO2 interface was very rapidly sealed off by Al2TiO5 formation. Reactant transport across the Al2TiO5 was slow because of the low mobilities in the product phase. Therefore, much lower product growth velocities were observed at higher temperatures than at lower temperatures. |
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