Mullite ceramics were fabricated from boehmite/silica diphasic gels using a
rotary forging compaction technique and pressureless sintering. Almost ful
ly dense mullite samples were obtained after sintering at 1350 degrees C fo
r 2 h. The microstructure of sintered samples comprised fine (average size
<1 mu m), equiaxed grains. The samples showed superior sintering behaviour
in comparison to those fabricated using conventional uniaxial and isostatic
pressing. Powder compaction by rotary forging is thought to generate visco
us deformation of the contact points increasing the interparticle contact a
rea as well as increasing the packing density by breaking clo,vn hard agglo
merates more effectively with concomitant rearrangement of the primary powd
er particles, thus promoting-greater densification at relatively low temper
atures.