Preparation of Al2O3 ceramics with long-range inter-locked platelet structures possessing high porosity and excellent mechanical strength

Abstract

Porous Al2O3 ceramics with long-range inter-locked platelet structures were prepared by a facile gel-casting method using cryolite and β-SiC as additives. An extremely high mass transfer efficiency for the construction of the long-range inter-locked platelet structures was provided by NaAl11O17 and NaAlSiO4, which are generated through chemical reactions of additives during sintering. Moreover, the effect of additive content on the evolution of the inter-locked platelet structures was discussed, while the relationship between the inter-locked platelet structures and the compressive strength and thermal conductivity of porous Al2O3 ceramics was also investigated. The sample with 1.5 wt% β-SiC and 15.0 wt% cryolite had a long-range inter-locked platelet structure, which exhibited excellent compressive strength (60.5 MPa) while maintaining high porosity (53.4 %). Interestingly, the long-range inter-locked platelet structures were capable of rapid heat transfer, while the localized inter-locked platelet structures had a great thermal insulation effect.