Abstract: Al2O3/ZrO2 gradient composite ceramic tool material was prepared by vacuum hot pressing sintering， and the content of ZrO2 and the layer thickness ratio of gradient structure were optimized. The Vickers hardness， flexural strength and fracture toughness of AZE20 gradient composite ceramic tool material with layer thickness ratio of 2.0 are （18.7±0.33） GPa， （937±28.5） MPa and （8.2±0.32） MPa·m1/2 respectively. Compared with the homogeneous ceramic tool material AZ20 with the best ZrO2 content， the Vickers hardness， flexural strength and fracture toughness are increased by 22%， 37.8% and 43.8%， respectively. The design of the gradient structure makes the surface layer form the residual compressive stress， the grain is refined to a certain extent， and more ZrO2 grains are stable in the T-phase ZrO2 grain size due to the size of the residual compressive stress. It is found that the fracture mode of the composite is the combination of the transgranular fracture of the surface layer and the intergranular fracture of the middle layer， and this hybrid fracture mode improves the overall mechanics properties. 

Key words: ceramic tool material, gradient structure, residual compressive stress, hybrid fracture, mechanics property

摘要： 采用真空热压烧结方式制备了Al2O3/ZrO2梯度复合陶瓷刀具材料，并对ZrO2含量及梯度结构层厚比进行了优化。层厚比为2.0的AZE20梯度复合陶瓷刀具材料维氏硬度为（18.7±0.33） GPa，抗弯强度为（937±28.5） MPa，断裂韧性为（8.2±0.32） MPa·m1/2，相比最佳ZrO2含量的均质复合陶瓷刀具材料AZ20，维氏硬度、抗弯强度和断裂韧性分别增加了22%、37.8%和43.8%。梯度结构的设计使表层形成残余压应力，晶粒得到一定程度的细化，更多的ZrO2晶粒因残余压应力尺寸稳定在t相ZrO2晶粒尺寸。在复合材料断口形貌中发现，其断裂方式为表层穿晶断裂和中间层沿晶断裂的结合，这种混合断裂方式使刀具整体力学性能得到提高。

关键词: 陶瓷刀具材料, 梯度结构, 残余压应力, 混合断裂, 力学性能