Effect of Milling Time and Sintering Techniques on Compactness of Al_2O_3/B_4C Pellets

A1_2O_3/B_4C 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 1550-1650℃,and the pellets' density decreased if the temperature was higher or lower.The best relative density and open porosity of Al_2O_3/B_4C pellets hot pressed at 1600℃were 96.41%and 0.08%,respectively.Hot pressed Al_2O_3/B_4C pellets got densified quickly,that the densification temperature was lower above 100℃than the pressureless sintered one, and the microstructure was fine and uniform.