摘要
通过在铝热剂中引入适量的ZrO2粉末，基于铝热氧化-还原反应、重力下陶瓷／金属液相分离，以大过冷条件下熔体共晶生长方式，制备出以ZrO2正方相纳微米纤维镶嵌于其上且长径比为8．0～12．0的蓝宝石棒晶及少量α-Al2O3片晶为基体的Al2O3／ZrO2自生复合陶瓷。通过材料力学性能测试与裂纹扩展路径观察，研究复合陶瓷显微结构与其力学行为之间的关系。结果表明，复合陶瓷的弯曲强度与断裂韧度分别达到1256MPa与13．2MPa·m^1/2；分布于蓝宝石棒晶上大量的面间距为纳微米尺度的Al2O3／ZrO2两相低能界面及残余压应力，使蓝宝石棒晶与陶瓷基体得以强化，迫使裂纹沿蓝宝石棒晶边界偏转；同时，因处于裂纹尖端尾部的蓝宝石棒晶桥接与拔出、α-Al2O3片晶桥接与摩擦互锁等效应，又使裂纹扩展呈现出强烈的稳定化倾向。
Al_2O_3/ZrO_2(4Y) self-growing composite ceramics, which is composed of major rod-shaped sapphires with 8.0~12.0 aspect ratio and minor lamellar α-Al_2O_3 phase, and within the sapphires t-ZrO_2 nano-micron fibers are embedded, has been prepared with eutectic growth of melts in the condition of severe undercooling degree by introducing proper ZrO_2 (4Y) powder into the thermit on the basis of oxidation-reduction reaction of the thermit and liquid-liquid phase separation of ceramics/metal under the gravity, the relationship of microstructure with mechanical behavior has been understood by measuring mechanical properties of the composites and observing crack propagation paths. The results show that the flexural strength and fracture toughness of ceramic composites are 1 256 MPa and 13.2 MPa·m~ 1/2 , respectively. A number of low energy interface in a nano-micron scale distance between Al_2O_3/ZrO_2(4Y) and compressive residual stress in the sapphires results in the reinforcement of the rod-shaped sapphires and ceramics matrix, which exerts the crack to propagate along the rod-shaped sapphires. Meanwhile, crack-bridging and pull-out of sapphires, crack-bridging and frictionally interlocked effects of plate-like α- Al_2O_3 grain in the wake of crack tip also render the crack stabilization to arise.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2006年第11期681-684,共4页
Special Casting & Nonferrous Alloys
基金
国防"十一五"装备预研资助项目(51312010706B)
国家自然科学基金资助项目(50671312)
中国人民解放军军械工程学院科研基金资助项目(YJJXM05001)
