纳米增强金属陶瓷的组织及热冲击性能

为了进一步提高金属陶瓷的力学性能及其刀具的高速切削性能, 研究了纳米增强金属陶瓷的显微组织特征和热冲击性能。扫描电镜和透射电镜分析表明: 组织中陶瓷相呈现典型的芯2壳结构特征; 芯为TiC 或Ti (C ,N) , 而壳则为( Ti ,Mo ,W) (C ,N) 固溶体。纳米增强金属陶瓷机制为细晶强化、弥散强化和固溶强化。热冲击实验表明: 随着热循环的进行, 材料中孔洞的数量、孔洞的尺寸以及微裂纹的尺寸随之增大; 同时, 热循环过程中出现的表面氧化、裂纹长大、偏转以及桥接现象也很显著。与常规Ti (C ,N) 金属陶瓷相比, 纳米增强金属陶瓷的抗热冲击性能明显提高。

Microstructural characteristics and thermal shock resistance ofnano-powder reinforcing cermets

Microstructural characteristics and thermal shock resistance of nano-powder reinforcing Ti(C,N) based cermets were investigated in order to efficiently improve the mechanical properties of Ti(C,N) based cermets and the high-speed cutting behaviors of cermets cutters.SEM and TEM analyses show that the coarser ceramic particles exhibit a typical core-rim structure(core is usually referred to as TiC or Ti(C,N) and rim is virtually a(Ti,Mo,W)(C,N) solid solution).The nano-powder reinforcing mechanisms can be summarized as grain fining strengthening,dispersion strengthening and solid solution strengthening.The thermal shock tests on nano-powder reinforcing(cermets) and conventional cermets show that the quantity and size of the voids plus the size of micro-cracks in both cermets increase and other phenomena such as surface oxidation,cracks growth,cracks deflection and cracks brid-(ging) are found to become increasingly apparent with thermal shock cycles,and the nano-powder reinforcing cermets possess a better thermal shock resistance in comparison with conventional cermets.