Effects of β-Si_3N_4 Seeds Addition on Microstructure and Mechanical Properties of Porous Si_3N_4 Ceramics

摘要

Porous Si_3N_4 ceramics were prepared by conventional sintering method with the initial Si_3N_4 powder added different amounts of β-Si_3N_4 seeds and 5 wt.% Y_2O_3. The porosity, density and flexural strength were tested by Archimedes and three-point bending methods, respectively. Microstructure of porous Si_3N_4 ceramics was studied by scanning electron microscopy. The results showed that the fibrous β-Si_3N_4 grains developed in the bimodal porous microstructure and the average aspect ratio of 6.42 by adjusting the β-Si_3N_4 seeds content up to 3 wt.%. Under the porosity of about 42%, the flexural strength of the materials could reached 315.98 MPa.