Study On Material Removal Mechanism Of Ultrasonic Vibration-assisted Polishing For Monocrystal Silicon

With the development of high and new technologies,the requirement of industrial equipment to parts is higher and higher,especially surface quality.In recent years,a variety of hard and brittle materials have been widely used in aerospace,optics,electronics,military,and other industries with their excellent performance.While the demand is increasing,the surface quality requirements of workpieces are gradually increasing.The hard and brittle materials are high hardness and brittleness,there is a problem that it is difficult to obtain a smooth surface with high efficiency.In this paper,single crystal silicon is taken as the research object,and the material removal process of ultrasonic vibration-assisted polishing of single crystal silicon is studied in order to obtain high processing efficiency and surface quality,and guide the industrial production process.In this paper,through theoretical analysis and the establishment of material removal rate equation,simulation of the single abrasive particles to remove single crystal silicon under ultrasonic vibration and the construction of an experimental platform for ultrasound vibration polishing experiments,the paper analyze the material removal mechanism and the influence of various factors on the removal process.The main research contents of the thesis include:(1)Combining ultrasonic vibration,Hertz elastic contact,friction theory,statistics,and other related theories,the the distribution of polishing pad’s peak and abrasive particles under different pressures were analyzed and the material removal rate equation is established for the two-body scratch wear;According to the elasto-plastic deformation and Hertz contact law,the maximum intrusion depth and contact time caused by free abrasives impacting the workpiece surface were studied.(2)Smoothed Particle Hydrodynamics Method coupling and Finite Element Method were used to establish a model of micro-scale ultrasonic vibration scratching single-crystal silicon,and the ultrasonic vibration frequency and amplitude on the workpiece surface metamorphic layer,stress,cutting force and friction are studied;At the same time,the distribution of stress and strain,the thickness of metamorphic layer,the change of potential energy and cutting force in the process of ordinary scratching and ultrasonic vibration assisted scratching are also analyzed and researched.(3)According to the theory of molecular dynamics,a model of single-crystal silicon scratching with ultrasonic vibration under nanometer scale was established,and the cutting force,potential energy,stress,and single abrasive material removal and phase change in ordinary scratching and ultrasonic vibration were compared and analyzed.The factors that affect the degree of amorphization and the removal of single abrasive materials were also studied and analyzed.(4)An experimental platform was set up,and ultrasonic vibration-assisted polishing experiments were performed on single-crystal silicon.A prediction model of surface roughness was established using neural network.The orthogonal test and quadratic polynomial regression analysis were used to discuss the experimental results.Through the orthogonal analysis and two polynomial regression analysis of the experimental results,the effect of each variable on the experimental results was analyzed.