采用热压烧结方法分别制备了Al2O3-TiCN复合陶瓷(AT)及掺杂MgO-Y2O3复合助剂的Al2O3-TiCN复合陶瓷(ATMY); 研究了烧结温度和MgO-Y2O3复合助剂对复合陶瓷相对密度、显微组织及力学性能的影响。结果表明: 当烧结温度在1 400～1 600 ℃时, AT和ATMY的相对密度均在97.3%以上; 当烧结温度不超过1 500 ℃时, 利用第二相TiCN可有效抑制Al2O3晶粒长大, AT和ATMY的显微组织、断裂韧度均无明显差异; 当烧结温度超过1 500 ℃时, TiCN不能有效地抑制Al2O3晶粒长大, 导致AT显微组织粗化, 在1 600 ℃烧结的AT的断裂韧度为4.5 MPa·m1/2; 掺杂了MgO-Y2O3复合助剂后可与TiCN协同抑制Al2O3晶粒长大, 在1 600 ℃烧结的ATMY的显微组织细小均匀, 断裂韧度可达5.1 MPa·m1/2。

Al2O3-TiCN ceramic (AT) and MgO-Y2O3 doped composite ceramic (ATMY) were fabricated by hot-pressing sintering. The effects of sintering temperature and MgO-Y2O3 additive on the relative density, microstructure and mechanical property of composite ceramics were studied. The results show that the relative density of AT and ATMY was not less than 97.3% at the sintering temperature from 1 400 ℃ to 1 600 ℃. When the sintering temperature was no more than 1 500 ℃, the second phase of TiCN could effectively inhibit grain growth in Al2O3 substrate due to the grain boundary pinning effect, and there was no obvious difference between AT and ATMY of the microstructures and fracture toughness. When the sintering temperature was higher than 1 500 ℃, TiCN phase was unable to inhibit the grain growth of Al2O3, resulting in the microstructure coarsening of AT. The fracture toughness of AT sintered at 1 600 ℃ was 4.5 MPa·m1/2. The doped MgO-Y2O3 additive cooperated with the second phase of TiCN could effectively inhibit the grain growth in Al2O3 substrate. When sintered at 1 600 ℃, the microstructure of ATMY was small and uniform, and the fracture toughness reached as high as 5.1 MPa·m1/2.