Fabrication of hierarchically porous Si3N4 foam ceramics with stamen-like cell structure

Inspired from the stamen structure in nature, hierarchically porous Si3N4 foam with stamen-like cell structure is fabricated by using egg white protein as pore forming agent in the gel casting process. Macropores with micro-interconnected pore on the wall are present which have average pore size of 0.36 μm and 10-400 μm. Graded rod-shaped Si3N4 grains, finer ones with aspect ratios of 10 on the wall and longer ones with aspect ratios of 20 in the interior of the macropores, are synthesized. Such porous Si3N4 exhibits good mechanical property, relatively high strength (11.9 MPa) and high porosity (81.7%), indicating it is a potential high-temperature separation materials.