Constrained densification in boehmite-alumina mixtures for the fabrication of porous alumina ceramics

It is demonstrated that inherent constrained densification characteristics of the bimodal size distributed powders can be utilized to fabricate porous alpha alumina. Seeded boehmite was mixed with coarse alpha alumina particles to produce various compositions of bimodal mixtures. The densification behaviour of the mixtures was correlated with shrinkage and microstructural evolution. The mixtures sintered at 1200°C contained more than 30% porosity and the mechanical strength of the mixtures was increased by 2-4 fold relative to the coarse particles alone with similar porosity (< 5 MPa).