Ceramic foams with highly open channel structure from direct foaming method in combination with hollow spheres as pore-former

To satisfy the ever-increasing demands for high-performance ceramic foams that could be applied in catalysts loader, filtrations and adsorptions, it is critical to develop technologies for ceramic foams with open channel structure. In this work, we fabricated ceramic foams with three-dimensional porous structure specially with open channels by combining direct foaming method with adding pore-forming agent method. There are two levels of length scale present in this hierarchically porous structure, that is, foam structure with spherical pores evolved from bubbles, and open pores on the cell wall derived from silica hollow spheres with thin shell as the pore-former. Hierarchical ZrO 2 based foams with porosity of 86.5%-95.1% and compressive strength of 2.05-5.67 MPa, and Al 2 O 3 based foams with porosity of 86.2%-91.0% and compressive strength of 6.8-13.2 MPa were fabricated. The prepared ceramic foams characterized by this open channel structure are promising to perform outstandingly in the abovementioned fields due to their uniform pore size, low density as well as high mechanical strength.