烧结温度和复合助剂对 Al2 O3-TiCN复合陶瓷显微组织和性能的影响

摘要

采用热压烧结方法分别制备了 Al2 O 3-TiCN 复合陶瓷(AT)及掺杂 MgO-Y2 O 3复合助剂的 Al2 O 3-TiCN 复合陶瓷(ATMY)；研究了烧结温度和 MgO-Y2 O 3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1400~1600℃时,AT 和 ATMY 的相对密度均在97．3％以上；当烧结温度不超过1500℃时,利用第二相 TiCN 可有效抑制 Al2 O 3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1500℃时,TiCN 不能有效地抑制 Al2 O 3晶粒长大,导致 AT 显微组织粗化,在1600℃烧结的 AT 的断裂韧度为4．5 MPa.m 1%Al2 O 3-TiCN ceramic (AT)and MgO-Y2 O 3 doped composite ceramic (ATMY)were fabricated by hot-pressing sintering.The effects of sintering temperature and MgO-Y2 O 3 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 Al2 O 3 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 Al2 O 3 ,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-Y2 O 3 additive cooperated with the second phase of TiCN could effectively inhibit the grain growth in Al2 O 3 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 .