Effect of solid content on pore structure and mechanical properties of porous silicon nitride ceramics produced by freeze casting

摘要

Porous Si_3N_4 ceramics were prepared by freeze casting using liquid N_2 as refrigerant. The pore structure, porosity, a→ β-Si_3N_4 transformation and mechanical properties of the obtained materials were strongly affected by the solid contents of the slurries. Increasing the solid content would reduce the porosity, decrease the pore size and change the pore structure from the aligned channels with dendrites to the round pores with decreased pore size. The formation of this round pores impeded the a→β -Si_3N_4 phase transformation, but was beneficial to the mechanical properties of the obtained porous Si_3N_4 due to its unique pore structure.