Effect Of ZrC On The Microstructure And Mechanical Properties Of Ti(C,N)-based Cermets

As a new kind of tool materials, the Ti(C, N) -based cermets have been widely used in recent years due to many of their good properties. We prepared the samples that had different ZrC content by the traditional method of powder metallurgy and explained macro mechanical properties of this material by means of XRD, SEM, EDX and so on.The thesis is composed of five chapters. In the first chapter, the microstructure, properties of Ti(C,N)-based cermets as well as its development history were introduced. Meanwhile, the trend of nanocomposite ceramics was also briefed.In Chapter Two, experimental raw materials and preparation techniques of Ti (C, N)-based cermets were introduced simply. In Chapter Three, we focused on the testing method of mechanical properties.In Chapter Four, We discussed the composition-microstructure-property relationship of Ti(C, N)-based cermets, and we reviewed the effect of different ZrC content on the microstructure and mechanical properties of cermets. The conclusion of this study can be summarized as follows:(1)Within a certain range, the microstructure became finer with the increasing of ZrC powder addition and the solid solution of (Ti,Zr)C,(Ti,Mo)C,(Ti, Zr,Mo)C,(Ti,Mo,W)C,(Ti,Zr,Mo,W)C formd, which was helpful to improve the strength and toughness of the material.What' more, there was classical black core/grey rim structure in the microstructure.(2)An interesting white round grain appeared in TiC-based cermets and a new type white core/grey rim structure appeared in Ti(C,N)-based cermets after the addition of ZrC, which was favorable to the mechanical properties.(3)Microcrack-toughening mechanism has been assumed as the main factor which is responsible for the toughening effect.(4)The results show that the relative density of Ti (C,N)-based cermets added by ZrC is not good enough, because the wettability of ZrC in metal phase is not perfect, which has effect on the fracture toughness and hardness badly.Chapter Five summarized the whole thesis and gave some advice on future works.