High-Strength Porous Alumina Ceramics by the Pulse Electric Current Sintering Technique

High-strength porous alumina has been fabricated with a microstructure control using the pulse electric current sintering (PECS) technique. During sintering the discharge, which is assumed to take place in the voids between the particles, is thought to promote the bridging of particles by neck growth in the initial stages of sintering, leaving high porosity. The effect of dopants (MgO, 200 ppm; TiO₂, 1000 ppm) and of secondary inclusions (3 vol% 3Y-TZP) on the constrained densification and the improvement in the mechanical behavior of porous alumina ceramics has been reported. The porosity of the fabricated porous alumina was controllable between 30% and 50% depending on the sintering temperature. The flexural strength of alumina having 30% and 42% porosity showed impressive values of 250 and 177 MPa, respectively. The dominance of the preferential neck growth of grains over densification significantly improved the mechanical properties of porous alumina, besides leaving high porosity.