Synthesis of honeycomb-like structured porous Si3N4 ceramics with exceptionally high number of cells per square inch

•Porous Si3N4 ceramics were prepared by the self-organization method of alginate.•The obtained porous Si3N4 ceramics possess high cell density of 58000 cpsi.•The prepared Si3N4 ceramics possess interesting hierarchical pore structure.•The obtained ceramics have highly ordered channels and well mechanical strength.•The microstructure and properties of the sample can be effectively controlled.

Honeycomb-like structured porous Si3N4 ceramics with exceptionally high number of cells per square inch were prepared by the self-organization method of alginate. The obtained samples have highly ordered channels, high porosity and well mechanical strength. It is found that the microstructure and properties of obtained porous Si3N4 ceramics can be effectively controlled by choosing different kinds of alginates. And it is worth to note that the obtained ceramics possess interesting hierarchical pore structure, including the unidirectionally aligned channels with pore size of 50–120 µm (first pore structure) and the interlocked microstructure of fibrous β-Si3N4 grains within channel walls with pore size of 0.8–2.6 µm (secondary pore structure), making it desirable for filter applications.