Fabrication of high-performance pure alumina ceramics with defect-rich structures by dynamic sinter forging

In this study, α-Al2O3 was sintered by dynamic sinter forging (DSF). The grain growth, mechanical properties and microstructures of the resultant ceramics were investigated in detail. The results showed that the grain growth during DSF was dominated by a dynamic grain growth process, in which grain size increased with an increase in pressure. The flexural strength of the ceramics increased with increasing pressure and reached 770 MPa in the sample prepared at 1300oC and 100 ± 10 MPa, which was significantly higher than that of the samples prepared by hot pressing and hot oscillatory pressing. The high strength was contributed to the severe plastic deformation induced by the oscillatory pressures, which strengthened both grain boundaries and grains. The current study suggests that DSF is a promising technique for preparation of high-performance Al2O3 ceramics, better than hot pressing and hot oscillatory pressing.