Abstract
To determine the content of o′-phase in β′-o′sialon ceramics, green compacts of a Si3N4 powder and boehmite sol were oxidized at 900°-1050°C, followed by sintering and HIPing. The ratios of O/N in the prepared sialons were changed at a fixed ratio of Si/Al. X-ray diffractometry, optical and scanning electron microscopy, electron-probe microanalysis were used for examination. Optical and electronmicrographs coupled with image analysis showed that, with increasing oxidation temperature, the amount of o′-phase increased and its grain size decreased. The o′-phase contents determined were well correlated to that calculated from the XRD results. These results explained the densities of sialon ceramics.
