成型压力对Ti(C,N)基金属陶瓷微观组织结构和力学性能的影响

Effect of forming pressures on microstructure and mechanical properties of Ti(C,N)⁃based cermets

以Ti(C,N)为基体硬质相,Ni和Co为金属黏结相,WC、Mo_(2)C和TaC为第二相碳化物,借助真空热压烧结技术制备了Ti(C,N)基金属陶瓷,探究了成型压力对金属陶瓷物相组成、微观形貌和成分、相对致密度、显微硬度、断裂韧性和抗弯强度的影响.研究结果表明:成型压力并未改变金属陶瓷的物相组成,所有试样均展现出典型的芯-环结构;无压成型烧结制备出的金属陶瓷不仅具有典型的黑芯-灰白双环结构,还呈现另一种白芯灰环结构.同时,金属陶瓷的晶粒度得到了细化.力学性能测试结果表明:成型压力达到8 MPa,金属陶瓷的相对致密度、显微硬度、断裂韧性和抗弯强度达到最大值,分别为99.1%,19.39 GPa, 7.84 MPa·m^(1/2)和1 488 MPa.金属陶瓷的断裂模式主要为沿晶断裂,并呈现较多的韧窝和撕裂棱.

In this paper,Ti(C,N)⁃based cermets were prepared by vacuum hot pressing sintering technology with Ti(C,N)as matrix hard phase materials,Ni and Co as the metal binder,WC,Mo_(2)C and TaC as second phase carbides.The effects of forming pressure on phase composition,micromorphology and composition,relative density,microhardness,fracture toughness and flexural strength of cermets were investigated.The results show that the phase composition of cermets is not affected by forming pressure,and all samples show a core rim structure.The cermets prepared by pressureless sintering have a typical black core and grey⁃white rim and present another white core and grey rim structure.Simultaneously,the grain size of cermets has been refined.The test results of mechanical properties show that when the forming pressure reaches 8 MPa,the relative density,microhardness,fracture toughness and flexural strength of cermets reach the highest values,which are 99.1%,19.39 GPa,7.84 MPa·m^(1/2) and 1488 MPa,respectively.The fracture mode of cermets is mainly intergranular fracture,and there are many dimples and tearing edges.