基于分子动力学的SiC化学机械磨削材料去除机理研究

Research on Material Removal Mechanism of SiC Chemo-mechanical Grinding Based on Molecular Dynamics

为了研究SiC化学机械磨削的材料去除机理,采用Lammps分子动力学仿真软件建立O_(2)环境中SiO_(2)磨料化学机械磨削加工SiC的原子模型进行分析。仿真结果表明,O_(2)分子在磨粒的机械作用下和SiC表面的Si原子发生化学反应,生成SiO_(2)和SiO,并与C原子反应生成CO_(2)和CO。当磨削温度低于1200K时,磨削温度提高对SiC的表面活化能和O_(2)扩散速率影响较小,O_(2)消耗量约为300个,Si-O键生成数量约为370个。随着磨削温度提高到1600K,O_(2)扩散速率和化学反应速率提高,O_(2)消耗量超过340个,Si-O键生成数量超过440个。O_(2)浓度增大能够加快化学反应速率,Si-O键生成数量从376个增加到598个。当磨削深度从2A增大到6A时,原子去除数量从98个增加到265个,摩擦力增大2倍,同时磨削速度的提高能够提高材料去除率。基于分子动力学对O_(2)环境下SiC化学机械磨削的材料去除机理进行研究,发现SiC会和O_(2)发生化学反应,生成Si-O氧化膜和C-O气体,为SiC的化学机械磨削提供理论依据。

In order to investigate the material removal mechanism of SiC chemo-mechanical grinding,an atomic model of SiO_(2)abrasive chemo-mechanical grinding of SiC in O_(2)environment was established by using Lammps molecular dynamics simulation software for analysis.The simulation result shows that O_(2)molecule reacts chemically with Si atom on SiC surface under the mechanical action of abrasive grain to generate SiO_(2)and SiO,and reacts with C atom to produce CO_(2)and CO.When the grinding temperature is lower than 1200 K,the increase of grinding temperature has lttle effect on the surface activation energy and O_(2)diffusion rate of SiC.The amount of O_(2)consumed is about 300,and the number of Si-0 bond formed is about 370.As the grinding temperature is increased to 1600 K,the O_(2)diffusion rate and chemical reaction rate are improved,the O_(2)consumption is more than 340,and the number of Si-O bond formed exceeds 440.An increase in O_(2)concentration can accelerate the chemical reaction rate,and the number of Si-O bond generated is increased from 376 to 598.When the grinding depth increases from 2 A to 6 A,the number of atom removed is increased from 98 to 265,the friction force increases by 2 times,and simultaneously the increase in grinding speed can improve the material removal rate.Based on molecular dynamics,the material removal mechanism of SiC chemo-mechanical grinding in O_(2)environment was investigated.The result demonstrates SiC would react with O_(2)to produce Si-O oxide film and C-O gas,which provides theoretical basis for SiC chemo-mechanical grinding.