TiB_2-TiC复相陶瓷的结构与性能研究

STUDY ON THE STRUCTURE AND PROPERTIES OF TiB_2-TiC MULTIPHASE CERAMICS

TiB2-TiC复合粉制备的TiB2-TiC复相陶瓷的相对密度达99.8%,硬度为93.2HRA,断裂韧性为5.53MPa·m1/2。显微结构研究表明:TiB2-TiC烧结体体内的位错和残余气孔影响材料性能。复合粉烧结体晶粒尺寸细小,大小分布均匀,晶粒之间界面干净,无杂质沉积,烧结体中TiB2和TiC两相界面接合处元素B,C,Ti的含量存在梯度变化,都有利于烧结体性能提高。TiB2晶粒生长存在取向性。

By hot-pressing method, TiB2-TiC multiphase ceramics were fabricated from TiB2-TiC composites powders under the following sintering conditions: sintering temperature at 1700°C and 1800°C, pressure at 30 MPa, sintering time for 60 min. The relative density, the hardness and fracture toughness of TiB2-TiC multiphase ceramic at room temperature were 99.8%, 93.2 HRA and 5.53 MPa &middot m1/2 respectively. The residual porosities and dislocation in sintered ceramics went against the performance. The microstructure of TiB2-TiC multiphase ceramics from composite powders had smaller and more symmetrical grains than the TiB2-TiC ceramics sintered from the mixtures of TiB2 and TiG powders. The elements of B, C and Ti at the interface of TiB2 and TiC were distributed gradually. There were no impurities at the interface and the bonds between phases were strong, which probably has relation to the higher properties of TiB2-TiC multiphase ceramics. The growth of TiB2 in different crystal directions was different in TiB2-TiC multiphase ceramics.