TiC-TiB_2细晶陶瓷凝固组织、断裂行为与原位增韧  

Solidification Microstructure,Fracture Behavior and In-Situ Toughening of TiC-TiB_2 Fine-grained Composite Ceramics

作　　者：赵忠民[1] 张龙[1] 宋义刚[1] 何建强[1] 

机构地区：[1]军械工程学院

出　　处：《特种铸造及有色合金》2011年第11期986-989,993,共5页Special Casting & Nonferrous Alloys

基　　金：国家自然科学基金资助项目(51072229)

摘　　要：通过采用超重力下燃烧合成制备TiC-TiB2细晶陶瓷,研究了陶瓷凝固组织与晶体生长特征,探讨了陶瓷显微组织与断裂行为、增韧机制的关系。XRD、FESEM与EDS分析表明,TiC-TiB2复合陶瓷基体主要由大量细小的TiB2片晶及分布其周围的形状不规则的TiC相构成,TiB2片晶的形成是因其小平面晶体生长特性所致,而不规则TiC的晶体形貌则是因非小平面晶体生长特性及高的生长速率所造成的。陶瓷相对密度、硬度(HV)、弯曲强度及断裂韧度分别为98.6%、21.8GPa、650MPa、12.5MPa·m1/2,并且陶瓷增韧是小尺寸TiB2片晶的裂纹偏转、裂纹桥接、片晶拔出及摩擦互锁原位增韧机制协同作用的结果。Solidification structure and crystal growth of the TiC-TiB2 fine-grained ceramics which was prepared by combustion synthesis under high gravity were investigated,and the relationship between microstructure and fracture behavior as well as toughening mechanism was analyzed by XRD（X-ray diffraction）,FESEM（field emission scanning electron microscope） and EDS（energy dispersive spectrometer）.The results show that the composite ceramics matrix is composed of a lot of fine TiB2 platelets and irregular TiC grain surrounded the TiB2 platelets.The formation of TiB2 platelets is resulted from faceted crystal growth while irregular TiC grains are the results of non-faceted crystal growth and high growth velocity.Relative density,Vickers hardness,bending strength and fracture toughness of the ceramics reach 98.6%,21.8 GPa,650MPa and 12.5 MPa·m1/2,respectively.Ceramic toughening mechanism is attributed to the co-operation of crack deflection,crack-bridging and pull-up by small-size TiB2 platelets and frictionally-interlocking in-situ toughening effects.

关 键 词：TiB2-TiC复合陶瓷 快速凝固 细晶组织 断裂行为 原位增韧 

分 类 号：TQ174.1[化学工程—陶瓷工业]