Effects of β-Si3N4 Seeds Addition on Microstructure and Mechanical Properties of Porous Si3N4 Ceramics

Abstract

Porous Si3N4 ceramics were prepared by conventional sintering method with the initial Si3N4 powder added different amounts of β-Si3N4 seeds and 5 wt.% Y2O3. The porosity, density and flexural strength were tested by Archimedes and three-point bending methods, respectively. Microstructure of porous Si3N4 ceramics was studied by scanning electron microscopy. The results showed that the fibrous β-Si3N4 grains developed in the bimodal porous microstructure and the average aspect ratio of 6.42 by adjusting the β-Si3N4 seeds content up to 3 wt.%. Under the porosity of about 42%, the flexural strength of the materials could reached 315.98 MPa.