Enhanced mechanical strength of talc-containing porous kaolin prepared by a replica method

Recently, porous ceramics have received much interest in various applications, finding use in membranes, thermal insulation, catalytic substrates, and gas burner media owing to their outstanding thermal stability and chemical stability. To fabricate porous ceramics, many processing methods can be used. Particularly, reticulated porous ceramics prepared by the replica method are worthy of attention given their interconnected open pores with high porosity and a low pressure drop. Therefore, many researchers have studied reticulated porous ceramics using various raw materials, such as alumina, mullite, silicon carbide, cordierite and partially stabilized zirconia. However, there are few reports about reticulated porous ceramic based on kaolin, which is a low-cost raw material that can be sintered at low temperature. In this study, reticulated porous kaolin is fabricated via the replica method. To tailor the mechanical properties of the reticulated porous kaolin, the pore density of polyurethane foam (10–80 PPI (Pores Per Inch)) and the sintering temperature (1000–1300 ℃) of the kaolin slurry-coated polyurethane foams are controlled. To characterize the kaolin, scanning electron microscopy (SEM), mercury porosimetry, high-resolution micro-computed tomography (µCT), and a universal testing machine were used. When the reticulated porous kaolin with a pore density of 60 PPI was sintered at 1300 ℃, it showed compressive strength of 1.23 MPa.