Effect of Milling Time and Sintering Techniques on Compactness of Al₂O₃/B4C Pellets

Al2O3/B4C pellets sintered by hot-press were compared with those by pressureless, and the effects of sintering temperature and milling time on open porosity and density of the pellets were investigated. The microstructure, surface morphology and phase state were investigated by SEM and XRD. The results show that the powders milled for 4 h were beneficial to sintering. The pellets sintered by hot pressing were much better than those by pressureless sintering. The suitable temperature for sintering was in the range of 1 550-1 650 ℃, and the pellets′ density decreased if the temperature was higher or lower. The best relative density and open porosity of Al2O3/B4C pellets hot pressed at 1 600 ℃ were 96.41% and 0.08%, respectively. Hot pressed Al2O3/B4C pellets got densified quickly, that the densification temperature was lower above 100 ℃ than the pressureless sintered one, and the microstructure was fine and uniform.