Synthesis of sol-gel derived alumina powder: effect of milling and calcination temperatures on sintering behaviour

Boehmite powder has been prepared by hydrolysing aluminium iso-propoxide an d peptising with nitric acid. This amorphous boehmite undergoes a series of phase transitions (gamma-AlOOH --> gamma-Al2O3 --> delta-Al2O3 --> alpha-A l2O3) on heating. Thermal analysis and phase determination using XRD and IR spectra of powder calcined at different temperatures confirmed the phase t ransitions. The effects of dry and wet milling on powder particle size, sin terability, and microstructure of sintered bodies have been studied. Compac ts of wet milled powder calcined at 1000 degrees C attained 98% of theoreti cal density at 1600 degrees C.