Sintering behavior of α-Al_2O_3 nanopowders

In order to inquire into the sintering behavior and the processes of densification of the α-Al2O3 nanopowders,the α-Al2O3 nanopowders synthesized by the polyacrylamide gel method were used to sinter bulk Al2O3 ceramics.The presence of the α-Al2O3 seeds can evidently decrease the phase formation temperature of the α-Al2O3 synthesized by the polyacrylamide gel method and obtain the α-Al2O3 nanopowders at a lower temperature of 950℃.The relative density of the Al2O3 green body increases with increasing compaction pressure on the green compacts and the Al2O3 green compacts with relative density of 56.0% are obtained at compaction pressure of 1 420 MPa.The relative density of the sintered Al2O3 ceramics increases with increasing the starting relative density of the green compacts and sintering temperature and the Al2O3 ceramics with a grain size of 1~2 μm and a relative density of 95.7% were obtained by sintering the green compacts with relative density of 52.8% at 1 500℃.