Moleculardynamics Numerical Simulation Of Diamondanon-Polished Silicon Carbide

With the rapid development of microelectronics and optoelectronics,electronic components are gradually developing toward more demanding working environments such as miniaturization,light weight,radiation resistance,high temperature,high frequency,high power and so on.Therefore,the development of wide band gap silicon carbide semiconductors materials has broad application prospects.In the traditional machining process,the process is difficult to complete,and the processing efficiency is low,and the deformation damage of the internal material of the workpiece was difficult to observed.The molecular dynamics simulation research can timely and effectively reveal the principle of removing materials,phase transformation and subsurface damage of the during the process of ultra-precision polishing about micro-deformation.Based on the analysis of molecular dynamics polishing,cutting and grinding simulations at home and abroad,three-dimensional and three-body simulation model of diamond abrasive nano-polished silicon carbide workpieces were established by means of molecular dynamics theory and method.Through the analysis of the simulation results,the effects of different polishing pressures,different rotating torques and different polishing thicknesses on the materials removal,phase transformation and subsurface damage were studied.Firstly,a simulation model for the molecular dynamics of nano-polishing of silicon carbide was established.The effects of different polishing pressures on the potential energy of the silicon carbide workpiece system and the workpiece temperature were analyzed.The removal mechanism of the silicon carbide workpiece during the ultra-precision polishing process was discussed.The pressure on silicon carbide changes from small to large.The principle of removal is followed by a polishing mode in which the compaction removal,the furrow removal,and the large deformation cutting are occurred.The removal principle of the material is that plastic removal,and the amount of material removal increases exponentially with increasing pressure.From the analysis of the atomic coordination number,it is concluded that the pressure can induce the phase transition of silicon carbide.The higher pressure,temperature and hydrostatic pressure during the polishing process accelerate the transition of the silicon carbide workpiece,and increase the number of atoms occurring phase trnsformation.As the phase transition depth increases,the thickness of the subsurface damage increases.As the polishing pressure increases linearly,the atoms with coordination numbers 2decreases,the atoms with coordination numbers 3 increase linearly,respectively,and the number of coordination atoms of 1,4,5,and 6 approximates an exponential function.Secondly,a simulation model of the molecular dynamics of rotating abrasive grains on nano-polishing of silicon carbide was established.The effects of different rotating torques on the removal principle of silicon carbide workpieces are studied.Under different rotating torques,the removal principle of silicon carbide workpieces is a combination of furrowremoval and adsorption removal.When the rotational torque is 2 ev,the processed surface quality of the silicon carbide workpiece is the best.As the rotational torque increases,the phase transition depth of the material decreases,and the phase transformation atomic weight of the material does not change obviously.Then the effects of different polishing thickness on the nano-polishing mechanism of silicon carbide workpieces were studied.With the increase of polishing thickness,the material removal principle will transform from adsorbed and removed the polishing mode to the combination of adsorption removal and furrow removal.As the polishing thickness increases,the system potential energy of the workpiece increases,and the phase transformation thickness of the material increase.The larger number of phase transformation atoms,the more serious subsurface damage thickness of the material.