摘要
稀土元素被认为是可以有效改善TiCN基金属陶瓷性能的添加剂,但其在高Mo_(2)C含量下的效果尚未得到深入研究。本研究采用真空热压烧结技术,在1500℃下制备了不同La_(2)O_(3)含量的Ti(C,N)-WC-Mo_(2)C-Cr_(3)C_(2)-Ni-Co金属陶瓷,其中Mo_(2)C含量为12 wt.%。对不同La_(2)O_(3)添加量(0.5 wt.%、1.0 wt.%、1.5 wt.%和2.0 wt.%)对Ti(C,N)基陶瓷显微组织和力学性能的影响进行了参数化分析。结果表明,当La_(2)O_(3)含量增加到1.0 wt.%时,芯相的比例增加,脆壳相的比例减少;在陶瓷相晶界上形成的纳米结构,有效抑制了壳相组织的异常长大,这使得金属陶瓷的脆壳相变薄,硬质相颗粒细化,从而提高了其硬度和断裂韧性等力学性能。当La_(2)O_(3)的添加量从1.5 wt.%增加到2.0 wt.%时,La_(2)O_(3)团聚形成直径约100 nm的较大颗粒,大幅度降低了金属陶瓷的力学性能。当La_(2)O_(3)添加量为1.0 wt.%时,Ti(C,N)基陶瓷的综合力学性能最佳,其维氏硬度和断裂韧性分别为16.55 GPa和6.14 MPa·m^(1/2)。本研究有助于进一步揭示稀土氧化物对高Mo_(2)C含量Ti(C,N)基陶瓷芯壳结构和力学性能的影响。
Rare earth elements were considered alternative additives beneficial to the TiCN based cermets,but their effect with high content Mo_(2)C has not been thoroughly investigated.In this study,Ti(C,N)-WC-Mo_(2)C-Cr_(3)C_(2)-Ni-Co cermets containing 12 wt.%Mo_(2)C doped with different contents of La_(2)O_(3)were prepared by vacuum hot-press sintering at 1500℃.Parametrical analysis on La_(2)O_(3)addition(0,0.5 wt.%,1.0 wt.%,1.5 wt.%,and 2.0 wt.%)was conducted,in terms of microstructure and mechanical properties of Ti(C,N)based cermets.Experimental results show that when the content of La_(2)O_(3)increases from 0 to 1.0 wt.%,the ratio of core phase increases while the ratio of brittle rim phase decreases.Nanostructure is formed on the grain boundary of ceramic phase,which effectively inhibits the abnormal growth of rim structures.This can thin the brittle shell,coarsen the core phase,and refine the grains,thus improving its mechanical properties,including hardness and fracture toughness.When the addition amount of La_(2)O_(3)increases from 1.5 wt.%to 2.0 wt.%,it will aggregate to form larger particles of about 100 nm,which sharply reduces its mechanical properties.The optimal La_(2)O_(3)addition is 1.0 wt.%,in which Ti(C,N)-based cermets show the optimal comprehensive mechanical properties:the Vickers hardness and fracture toughness are 16.55 GPa and 6.14 MPa·m^(1/2),respectively.This work provides further knowledge about the effect of rare earth on the core-rim structure and mechanical properties of Ti(C,N)-based cermets with high Mo_(2)C contents.
作者
邱昊
李小强
江晨阳
潘存良
屈盛官
QIU Hao;LI Xiao-qiang;JIANG Chen-yang;PAN Cun-liang;QU Sheng-guan(National Engineering Research Centre of Near-net-shape Forming Technology for Metallic Materials,South China University of Technology,Guangzhou 510640,China)
基金
Project (51474108) supported by the National Natural Science Foundation of China
Project (208081725043) supported by the Natural Science Foundation of Guangdong Province,China
Project (1203) supported by the Innovation-driven Development Science and Technology Project of Economic Development District of Yichun,China。
关键词
碳氮化钛基金属陶瓷
稀土
氧化镧
芯壳结构
断裂韧性
Ti(C,N)-based cermets
earth elements
La_(2)O_(3)
core-rim structure
fracture toughness
