不同碳/氮比的Ti(C x , N1- x )基金属陶瓷的显微组织与性能

Microstructure and Properties of Ti(C x ,N1- x )-based Cermets with Different C/N Ratios

摘要:

Ti(C_x,N_1-x)基金属陶瓷是用不同碳氮比制造的。研究了碳/氮比对芯-环结构和金属陶瓷性能的影响。结果表明，由于孔太多， Ti(C_0.5,N_0.5)基金属陶瓷的性能较差。随着碳/氮比的增加，白核/灰环的形成率降低，并且微观结构的均匀性增强。因此，基于 Ti(C_0.7,N_0.3)的金属陶瓷显示出优异的力学性能，但有少量的孔隙和较低的相对密度。与Ti(C_0.7,N_0.3)基金属陶瓷相比，TiC基金属陶瓷在没有N元素的情况下具有较高的相对密度且无孔隙，但其晶粒较粗大。为了获得细晶粒和高密度的显微组织，将0.25%Cr₃C₂-0.75%VC（质量分数）引入到TiC基金属陶瓷中，获得了优异的硬度、横向断裂强度和韧性。另外，在Ti(C_0.7,N_0.3)基金属陶瓷中也添加了0.25%Cr₃C₂-0.75%VC，但其力学性能低于Ti(C_0.7,N_0.3)的金属陶瓷，这是因为细颗粒和反应颗粒与Ti(C,N)发生了急性固溶反应。研究了基于不同C/N比的Ti(C_x,N_1-x)基金属陶瓷的切削性能和摩擦性能。结果表明，具有0.25%Cr₂C₃-0.75%VC的TiC基金属陶瓷在室温下的摩擦系数最低，为0.15，在1000 r/min的高速切削过程中，使用寿命最长。

Abstract:

Ti(C_x,N_1-x)-based cermets are fabricated with different ratios of carbon to nitrogen. The effect of C/N ratio on the core-rim structures and properties of cermets was studied. The results indicate that Ti(C_0.5,N_0.5)-based cermets possess poor properties due to too many pores. With the increase of C/N ratio, the formation rate of white-core/gray-rims decreases, and the homogeneity of the microstructure is enhanced. Consequently, the Ti(C_0.7,N_0.3)-based cermets show excellent mechanical properties, but a spot of voids and low relative density. TiC-based cermets with excellent relative density and non-porosity can be achieved in the absence of N element, which have coarser grain compared with Ti(C_0.7,N_0.3)-based cermets. In order to achieve fine grains and high density microstructure, 0.25wt%Cr₃C₂-0.75wt%VC is introduced into the TiC-based cermets. Superior hardness, transverse rupture strength and toughness are achieved. In addition, 0.25wt%Cr₃C₂-0.75wt%VC is also added into the Ti(C_0.7,N_0.3)-based cermets, but its mechanical properties are lower than that of the Ti(C_0.7,N_0.3)-based cermets without 0.25wt%Cr₃C₂-0.75wt%VC addition, which is due to acute solid solution reaction of finer and reactive particles with Ti(C,N). The cutting and friction performances of Ti(C_x,N_1-x)-based cermets with different C/N ratios were also investigated. The results show that the TiC-based cermets with 0.25wt%Cr₃C₂-0.75wt%VC exhibit the lowest coefficient of friction which is 0.15 at the room temperature, and the longest service life during high speed cutting at 1000 r/min.