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 and peptising with nitric acid. This amorphous boehmite undergoes a series of phase transitions (γ-AlOOH → γ-Al2O3 → δ-Al2O3 → α-Al2O3 ) on heating. Thermal analysis and phase determination using XRD and IR spectra of powder calcined at different temperatures confirmed the phase transitions. The effects of dry and wet milling on powder particle size, sinterability, and microstructure of sintered bodies have been studied. Compacts of wet milled powder calcined at 1000°C attained 98% of theoretical density at 1600°C.