Effect of Sedimentation and Flocculation Pre-treatment of Starting Si3N4 and Al2O3 Powders on Room Temperature Strength of β-sialon (z=1)

The room temperature strength of β-sialon fabricated using a mixture of sedimented and flocculated Si3N4, and Al2O3 powders was investigated, in comparison with that achieved using Si3N4 and aluminum iso-propoxide solution, and that using as-mixed Si3N4, and Al2O3, respectively. This β-sialon showed an average strength of about 990 MPa. It was slightly lower than that when using an aluminum iso-propoxide solution, but approximately twice that of the sample using an as-mixed powder. The difference in strength among the specimens is interpreted in terms of the size and number of process-related internal defects resulting in a fracture origin. It could be concluded that the sedimentation and flocculation pre-treatment of the starting powders was very effective to increase the strength of β-sialon due to removing internal defects.