Preparation of interpenetrating ceramic-metal composites

Ceramic reinforced metals are attractive because of their enhanced
elastic modulus, high strength, tribological properties and low thermal
expansion. Most work in this sector has focused on particle- or
fiber-reinforced composites where the ceramic phase is not continuous.
This work presents aluminium-alumina composites where both phases are
interpenetrating throughout the microstructure. Ceramic preforms were
produced with sacrificial pore forming agents leading to porosities
between 50% and 67%. Pore wall microstructure was varied by changing
the sintering temperature. Permeability and strength was measured for
the porous preforms and infiltration results were compared with
theoretical predictions based on capillary law and Darcian flow. A
direct squeeze-casting process was used to infiltrate the preforms with
aluminium resulting in an interpenetrating microstructure on both
macropore and micropore scale.