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 deg C was used. Dilatometric study reveals that the formation of spinel starts above 1000 deg C for all the compositions and the linear expansion values are in good agreement with their expected values considering theoretically possible spinel content. The fall in expansion values was also observed and above 1350 deg C due to greater shrinkate 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.
