Abstract
The macroscopic inhomogeneity of Sialon ceramics was studied. There were two regions in the sintered body. One of regions was green region and the other was brown region. The fracture toughness of the sintered body with two regions had large difference, and the green region had low toughness. The regions were analyzed by UV spectroscopy, EPMA, XRD, SEM, and TEM. There was no difference in microstructure, but there was difference in electronic state, chemical composition, and crystal phase. From these fact, it is considered that the origin of macroscopic inhomogeneity is due to gas generated from decomposition of Sialon. The gas is shut in sintered body when densification is fast at surface, and the chemical composition of grain boundary or grain is changed by reaction with gas.
