Effect of manufacturing process on the properties of alumina sintered ceramics

Calcination of spray dried alumina granules considerably affected the microstructure and mechanical properties of the sintered body. In the present investigation, the morphology of the granule surface showed that the sizes of alumina particles in the granule prepared from calcination were significantly smaller than those in the uncalcined granules. Sintered body prepared from uncalcined granules had a duplex microstructure consisting of pores and non-equiaxed, large grains due to grain growth. In contrast, the specimens prepared from calcined granules consisted of mostly fine grains. Flexural strength of specimen prepared from calcined granules was 32% higher than that prepared from uncalcined granules. The specimens prepared from calcined granules achieved average strength of 502 MPa with a Weibull modulus of 20. In this study, we found that the pore defects was rather uniformly distributed, and its uniformity increased with increasing sintering temperature.