摘要
目的 研究氮化硅刀具切削GH4169的黏结扩散磨损机理,以及黏结扩散过程对刀具的摩擦因数、硬度、冲击韧性的影响,为氮化硅刀具的应用提供参考。方法 基于Lammps软件建立氮化硅刀具与镍基高温合金的切削模型,模拟切削过程,分析黏结和扩散情况。通过计算晶界和晶格处的空位形成能、空位迁移能及扩散激活能,得出扩散系数,在此基础上拟合生长因子,确定控制黏结物生长速率的因素。根据刀具径向分布函数判断刀具是否因黏结磨损而产生新化合物,进而研究其对刀具性能的影响。结果 Ni、Fe、Cr等3种原子晶界处的扩散激活能分别为5.29、2.15、0.7 eV,晶格处的扩散激活能分别为5.58、3.42、1.14 eV,且扩散难易程度由大到小依次为Ni、Fe、Cr,扩散系数由大到小依次为Cr、Fe、Ni。在1 200 K下,Cr、Ni、Fe原子的生长因子分别为0.3、0.2、0.28。在刀具径向分布函数中,键长r=0.173 nm处的峰值逐渐降低,同时,键长r=0.235 8 nm和键长r=0.247 5 nm处的峰值增大。新生成的镍硅化合物可承受的压应力为6.541 GPa,Si3N4可承受的压应力为18~21 GPa。在扩散前后,2个模型的冲击韧性分别为169.1、187.8 eV/nm。结论 Ni、Fe、Cr原子易在晶界处发生扩散。在黏结物的生长过程中,Ni、Fe的生长速率由反应速率控制,而Cr的生长速率主要由扩散速率控制,且在黏结过程中生成了新的镍硅化合物和硅铁化合物。黏结、扩散磨损导致刀具的摩擦因数增大,刀具的硬度降低,但冲击韧性提高了约11.6%。
In order to study the bond diffusion wear mechanism of ceramic tools(silicon nitride tools)when cutting nickel-based superalloys GH4169 and the effects of wear on the friction coefficient,hardness and impact toughness of the tools,LAMMPS software is used to establish a cutting model of silicon nitride tools and nickel-based superalloys based on molecular dynamics(MD)methods to analyze the adhesion diffusion phenomenon of the tools by simulating cutting.By calculating the vacancy formation energy and vacancy migration energy of the atoms of the workpiece,the diffusion activation energies of Ni,Fe and Cr atoms are obtained.On this basis,the growth factors are fitted to determine the factors that control the growth rate of the adhesive.It aims to determine whether the tool has produced new compounds due to adhesive wear based on the radial distribution function of the tool,and then study its impact on tool performance.The diffusion activation energies at the grain boundaries of Ni,Fe,and Cr atoms are 5.29 eV,2.15 eV,and 0.7 eV,respectively.The diffusion activation energies at the lattice are 5.58 eV,3.42 eV,and 1.14 eV,respectively.The three atoms of Ni,Fe and Cr are more likely to diffuse at the grain boundary than at the crystal lattice,and the ranking of diffusion difficulty is:Ni>Fe>Cr,and the ranking of diffusion coefficient sizes is:Cr>Fe>Ni.The adhesion diffusion between the tool and the workpiece can be regarded as an interface reaction connection.The interface reaction growth kinetics is used to study the diffusion depth of the tool and the workpiece atoms is obtained.The simulating temperature is set at 1200 K for 30 min,and the growth factors of Ni,Fe and Cr atoms are obtained by fitting and they are CCr=0.3,CNi=0.2,CFe=0.28.Through the analysis of growth factors and diffusion depth,three controlling factors of atomic growth rate are determined.The growth rate of Ni and Fe is controlled by the reaction rate,while the growth rate of Cr is mainly controlled by the diffusion rate.According to the simulated cutting process,the change of the coefficient of friction of the tool is obtained.The results show that when the binder is bonded to the surface of the tool,the friction coefficient increases and the coefficient of friction is drastically decreased when the binder falls off.Through the change of the radial distribution function of the tool,it is proved that during the cutting process,the workpiece combines with the tool atoms under the action of high temperature and produces new compounds.By comparing the hardness of the new compound with the original tool material,it can be seen that the formation of the new compound leads to a decrease in the hardness of the tool.The impact model of the rigid block and silicon nitride is established based on LAMMPS,and it is found that the impact toughness of the silicon nitride is increased by about 11.6%compared with that before the bond diffusion.
作者
范依航
贾晓羽
郝兆朋
FAN Yihang;JIA Xiaoyu;HAO Zhaopeng(School of Mechanical and Electrical Engineering,Changchun University of Technology,Changchun 130012,China)
出处
《表面技术》
北大核心
2025年第17期80-90,182,共12页
Surface Technology
基金
国家自然科学基金(52375404)。
关键词
镍基高温合金
氮化硅刀具
分子动力学
黏结磨损
扩散磨损
nickel-based superalloy
silicon nitride tool
molecular dynamics
bonding wear
diffusion wear
