Mechanical characterization of highly porous β-Si_3N_4 ceramics fabricated via partial sintering & starch addition

摘要

In this study, porous β-Si_3N_4 ceramics containing limited amount of Sm_2O_3 and CaO as sintering aids were produced by addition of potato starch (10 and 20 vol.%) and partial sintering. Two different Si_3N_4 powders, a- and (3-, were used as starting materials. Scanning electron microscopy investigations revealed that development of elongated β-Si_3N_4 grains were much more pronounced when α-Si_3N_4 starting powder was used. Even though porosity values of the compositions prepared by using α-Si_3N_4 (~57.0-58.4%) is significantly higher than the samples produced by p-Si3N4 (42.6%), no significant change was observed for the bending strength, fracture toughness and Weibull modulus. This indicates that microstruclural features have a significant contribution to the mechanical properties of the porous materials in terms of bending strength and fracture toughness.