Kinetic analysis of magnesium aluminate spinel formation: Effect of MgO:Al2O3 ratio and titania dopant |
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| Authors: | Mostofa Shamim Somnath Sinhamahapatra Jahangir Hossain Sayan Lahiri Kausik Dana |
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| Affiliation: | Refractory and Traditional Ceramics Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032, India |
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| Abstract: | The mechanistic pathway of MgO-Al2O3 reaction in solid state to form MgAl2O4 spinel was investigated to correlate the kinetic parameters with ratio of reactants (MgO:Al2O3) and with the presence of a doping agent, TiO2. The time-temperature-expansion data of oxide compacts was analyzed using several model free analyses and model based (linear and non-linear) kinetic algorithms. These indicated that spinel formation process can be best described by single step with n-dimensional Avrami equation for every MgO:Al2O3 ratio, irrespective of titania dopant. The activation energy (Ea) of the process was proportional to % spinel formed in each system and validated with quantitative XRD analysis. The higher value of Avrami coefficient (n) in 90 wt% Al2O3 compositions has been explained with geometric considerations of powder packing. Incorporations of 1% TiO2 in the MgO: Al2O3 oxide compact did not markedly affect the reaction model, frequency factor and Activation energy. |
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| Keywords: | Spinel Activation energy Kinetics Avrami model Magnesia Alumina |
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