Spinellisation Study of Three Different MgO-Al₂O₃ Compositions Using a Dilatometer

Abstract

Three different MgO-Al₂O₃ spinel compositions having MgO: Al₂O₃ molar ratios 2: 1, 1: 1 and 1: 2 have been studied. Isostatically pressed green compacts of oxide mixtures were used for the dilatometric study and a maximum temperature of 1400°C was used. Dilatometric study reveals that the formation of spinel starts above 1000°C for all the compositions and the linear expansion values are in good agreement with their expected values considering theoretically possible (maximum) spinel content. The fall in expansion values was also observed at and above 1350°C due to greater shrinkage rate (from sintering) than the rate of expansion from spinellisation. The phase analyses of the final products showed spinel as the major phase with some free oxides due to incomplete spinellisation reaction.