纳米ZrO_2与微米Al_2O_3复合陶瓷的断裂模式

On the fracture model of nano ZrO_2/micro Al_2O_3 composite ceramics

研究了两种微米Al_2O_3与纳米ZrO_2复合陶瓷的裂纹扩展过程与显微结构的关系.结果表明,Al_2O_3晶粒内部形成纳米级或亚微米级ZrO_2颗粒,是复合陶瓷的断裂模式从沿晶断裂向穿晶断裂转化的主因.ZrO_2含量较低有利于Al_2O_3晶界迁移包裹纳米ZrO_2形成内晶结构;而ZrO_2含量较高使主晶相长大受到抑止,不利于形成内晶结构,趋向于沿晶断裂.裂纹穿晶扩展需要的驱动力比沿晶断裂大,故裂纹扩展阻力曲线的上升趋势更加显著.裂纹穿晶扩展路径主要取决于内晶颗粒产生的弹性应力场的性质.

The relationship between crack extension behavior and microstructure of the micro Al2O3-nano ZrO2 composite ceramics has been investigated. The results showed that the change of fracture model of the composite ceramics from intergranular into intragranular would be caused mainly by the nano/sub-microsized ZrO2 particles in the Al2O3 grains. Less ZrO2 content favors small sized ZrO2 particles wrapped in Al2O3 grains and formation of the intragranular structure by main boundary movement. But more ZrO2 results in that growth of main phase would be restricted and intragranular structure would be hard to form so that the fracture style tend to intergranular model. Crack extension resistance of intragranular fracture is more than intergranular fracture. The propagation paths of the cracks in grains are mainly decided by properties of inner-stress field caused by intragranular particles.