Porous alumina ceramics prepared by slurry infiltration of expanded polystyrene beads

Abstract

To produce highly porous MgO-doped alumina (Al2O3) ceramics, expanded polystyrene (EPS) beads were packed as a pore former and well-dispersed alumina slurry was used to infiltrate the pore space in the EPS bead compacts. The alumina particle-EPS bead green compacts were then heated to 1550°C in air to burn out the pore former and subsequently densify the MgO-doped alumina struts. The porous Al2O3 ceramics were featured with uniformly distributed open pore structures with porosities ranging from 72 to 78% and a pore interconnectivity of about 96%. The macropore size and the pore window size could be controlled by adjusting the size of the EPS beads and the contacting area between the EPS beads. The compressive strengths of the porous Al2O3 ceramics were in the range of 5.5–7.5 MPa, similar to those of cancellous bones (2–12 MPa). The porous alumina ceramics were further made bioactive after the dip coating of a sol-gel derived 58 S bioglass powder, followed by sintering at 1200°C.