PREPARATION OF ALUMINA BY A COMBINED PRECIPITATION AND GELATION PROCESS

Gels of aluminium hydroxide were prepared from aluminium sulfate solutions of varying concentration in order to check the possibility of higher yield. Thermal analysis of dried gel powders revealed the presence of aluminium hydroxide and aluminium sulfate, but both were amorphous to XRD. Calcination of gel prepared from solution of 0.5 mol/l concentration, at 1250 degrees C gave alumina particles in the size range 0.1-0.2 mu m. Sintering behaviour of this alumina powder has been studied and 99% theoretical density is achieved in 3 h at 1600 degrees C without MgO or grain growth inhibitor.