Preparation of novel reticulated porous ceramics with hierarchical pore structures

Abstract

Al2O3-ZrO2 reticulated porous ceramics (RPCs) with hierarchical pore structures were prepared by vacuum infiltration. Al(OH)3 was applied to provide the pore structure. Vacuum infiltration using an alumina/aluminum hydroxide slurry via a pre-sintering cycle was performed to fill up the hollow struts generated due to burnout of the polyurethane foam template and the coating on the Al2O3-ZrO2 ceramic struts. The results showed that as the Al(OH)3 content in the infiltration slurry was increased from 5% to 13%, the pore size distribution of the ceramic struts widened and the major pore size decreased. In addition, a compressive residual stress developed within the multilayered struts because of the difference in thermal expansion of the Al(OH)3-Al2O3 coating layer and Al2O3-ZrO2 ceramic struts. Moreover, with increasing Al(OH)3 content in the infiltration slurry, the porosity of the ceramic struts gradually increased, resulting in a decrease in Young's modulus and thermal conductivity, which influenced the compressive residual stress and thermal stress within the ceramic struts. Furthermore, the potential of the fabricated RPCs as catalyst supports was demonstrated.