Abstract: Considering the difficulty of sintering and leachability of alumina-based ceramic core, different contents of silica were added to the specimens. The porous alumina-based ceramic core was prepared using the dry pressing processes. The effect of different contents of silica, sintering temperature and sintering time on the properties of the alumina-based ceramic core were investigated. The results indicated that the linear shrinkages of the specimens sintered at 1500℃ and 1600℃ for 2 h were nearly the same. When the sample was sintered at 1700℃ for 2 h, the bending strength was decreased and the porosity was increased due to the evaporation of SiO₂. The shrinkage, bending strength, porosity and bulk-density of the specimens sintered at 1500℃ were invariable when the holding time exceeded 4 h. The sample sintered at 1500℃ for 2 h had linear shrinkage of 1.1%, bending strength of 63 MPa, the porosity of 35.5% and bulk-density of 2.29 g/cm³, which was hopeful to be the core candidate materials in high temperature application.

Key words: porous, alumina-based ceramic core, shrinkage, bending strength, porosity, bulk-density