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Kinetic analysis of spinel formation from powder compaction of magnesia and alumina
12-18-2020, 08:54 AM,
Post: #1
Kinetic analysis of spinel formation from powder compaction of magnesia and alumina
A kinetic investigation into the formation of spinel from alumina  fused alumina supplier(Al2O3) and magnesia (MgO) powder compaction with a stoichiometric mixing molar ratio of 1:1 was conducted in the temperature range of 1573 K to 1773 K over a certain time interval up to 25 h. The samples were pressed at pressures of 125, 375 and 750 MPa. The progress of the reaction was evaluated by monitoring the expansion ratio instead of the thickness of the spinel layer that was generated. The expansion ratio increases with increasing pressing pressure and holding time, and high temperature favored spinel formation. However, densification was observed at temperatures above 1673 K due to the occurrence of sintering between the powders. A kinetic model taking electrochemical potential as the driving force of the reaction was established, and the apparent activation energy was calculated to be 310.6 kJ/mol in the temperature range between 1573 K and 1673 K. The reaction was controlled by the inter-diffusion of Al3+ and Mg2+ ions in the spinel layer that was formed.https://hslabrasive.com
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