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

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.