Modeling And Simulation Of Micro Cutting Mechanism Of Single Crystal Silicon Carbide By Molecular Dynamics

Single crystal silicon carbide(SiC)materials have the advantages of high melting point and good thermal conductivity.They are widely used in high-power,high-frequency power devices such as turbine engine components,optical devices,and space telescopes.Due to the large hardness and high brittleness of SiC materials,the processing technology is complex and time-consuming,and the material utilization rate is low,which seriously hinders the further engineering application of SiC materials.At present,for SiC materials,in order to obtain good processing quality,as far as possible in its plastic area processing,the plastic domain processing of the material is at the nanoscale,the traditional macroscopic cutting research methods are not applicable.Therefore,the micro-scale cutting mechanism of SiC materials provides the basis for optimizing the cutting parameters and improving the quality of the parts.The molecular dynamics method,due to considering the microstructure and size effect of SiC material,has become the main research method of SiC micro-cutting simulation.In order to analyze the effects of cutting speed and cutting depth on the nano-machining process during the cutting process.In this dissertation,the micro-cutting simulations of single-crystal 3C-SiC materials were performed by molecular dynamics method.The tersoff potential function was chosen to describe the interaction between C and C,Si and Si,C and Si atoms.The lab developed LAMMPS open-source software to perform micro-cutting modeling on 3C-SiC materials to study the effects of different cutting speeds and cutting depth with different cutting force,and the influence of cutting temperature during the cutting process.The results show that the appropriate cutting speed is beneficial to reduce the damage layer thickness and improve the surface quality.At the same time,high speed cutting is beneficial to reduce the cutting force in the cutting process,and provides a theoretical basis for studying the cutting mechanism of hard and brittle materials in the nano-scale range.In order to verify the relationship between cutting force and cutting depth in molecular dynamics nano-machining process,nano-scratch test of SiC single crystal was performed using the nano-in-situ testing system TI950.The tangential displacement of the tool and normal displacement,tangential displacement and normal direction were obtained.Force,tangential displacement and relationship between tangential force curves,SEM observation of the scratch surface morphology.The simulation results and experimental results show that in the cutting process,the cutting force increases along with the increasing of the number of cutting tool atoms touching workpiece atoms,and the cutting force decreases with the increase of cutting depth.The cutting depth in the range of 0.5～1.5 nm,the smaller of the cut depth,the better of the surface quality.