基于分子动力学仿真的纳米胶体射流抛光材料去除机理

利用分子动力学模拟了纳米Si O2颗粒与单晶硅(100)表面的碰撞过程,以此来分析纳米胶体射流抛光的材料去除机理。仿真结果显示:粒径为7 nm的Si O2颗粒其速度在50 m/s时,与单晶硅工件表面的碰撞作用不会引起工件表面的原子排布的变化;而若要使碰撞对单晶硅工件表面原子排布产生影响,纳米Si O2颗粒的速度需大于250 m/s。以单晶硅工件为加工对象进行了纳米胶体射流抛光加工试验。利用激光拉曼光谱对加工前后单晶硅工件表面原子排布状况进行了比较,其结果与分子动力学仿真结果吻合。利用X射线光电子能谱,研究了加工前后纳米Si O2颗粒与单晶硅工件表面原子之间化学键的变化。通过仿真和试验得出:纳米胶体射流抛光中,纳米颗粒碰撞所产生的机械作用不能直接去除工件材料,材料的去除是纳米颗粒与工件表面之间机械作用和化学作用的共同结果。

Material Removal Mechanism of Nanoparticle Colloid Jet Polishing Based on Molecular Dynamics Simulation

The material removal mechanism of the nanoparticle colloid jet polishing was investigated by the molecular dynamics simulation of the collision between the SiO₂ nanoparticle and single crystal silicon workpiece (100). The simulation results show that the collision between the 7 nm nanoparticle with velocity of 50 m/s and the single crystal silicon workpiece cannot change the atom arrangement of the workpiece. When the velocity of the nanoparticle is higher than 250 m/s, the atom arrangement of the single crystal silicon workpiece can be changed. The machining of the nanoparticle colloid jet polishing process on the single crystal silicon workpiece was experimentally investigated. The atom arrangement of the single crystal silicon workpiece before and after machining was characterized by laser Raman spectroscopes. The results is in good agreement with that of the molecular dynamics simulation. The chemical bonds between the SiO₂ nanoparticle and the single crystal silicon atoms were also been studied by X-ray photoelectron spectroscopy. Both the simulated and experimental results show that the mechanical effects of nanoparticles during the nanoparticle colloid jet polishing process cannot remove the workpiece material directly. The removal of the material is the combined influence of the mechanical effect and chemical effect between the nanoparticles and the workpiece.