Simulation Study On Material Removal Technology Of Chemical Mechanical Polishing Of Nd:YAG Ceramic

With the rapid development of laser technology,solid-state lasers’ working material industry status gradually increase.Nd:YAG(Nd:Y3Al5O12,Nd-doped yttrium aluminum garnet)ceramic is a solid laser working material.People have higher and higher requirements on the surface quality of Nd:YAG ceramics to obtain higher-performance laser working material.The traditional polishing technology gradually cannot meet the surface quality requirements of Nd:YAG ceramics.Chemical mechanical polishing(CMP)is the only technology used in planarization and local processing.Applying CMP technology to the surface processing of Nd:YAG ceramics dramatically improves the surface quality of Nd:YAG ceramics.However,the researches on the surface CMP of Nd:YAG ceramics are not yet mature.Therefore,it is necessary to study the material removal technology of Nd:YAG ceramic CMP to provide some reference value for actual processing to further improve the surface quality of Nd:YAG ceramics.The schematic diagram of Nd:YAG ceramic CMP and the trajectory equation of a abrasive relative to the surface of Nd:YAG ceramic were established.On this basis,the trajectories of SiO2 abrasive relative to the surface of Nd:YAG ceramic is simulated by MATLAB software,and the influence of various relevant parameters on the trajectories of abrasives were analyzed.The effect of abrasive motion on the workpiece’s material removal and surface quality during Nd:YAG ceramic CMP was reflected from the side.The contact deformation and contact state between the workpiece,polishing pad,and abrasives in Nd:YAG ceramic CMP were analyzed.Combined with the trajectory equations of abrasives relative to the surface of Nd:YAG ceramic,the material removal rate model of single abrasive and the total material removal rate model were established.The influence of polishing pad speed,abrasive diameter,and concentration on the material removal rate was analyzed with the model.Based on computational fluid dynamics(CFD),the effect of polishing pad speed,abrasive diameter,and abrasive concentration on the surface pressure field,velocity field,and shear force field of Nd:YAG ceramic during CMP were simulated by finite element software,and compared with the established material removal rate model.The results show that the increase in the rotation speed of the polishing pad can make the pressure and shear force distribution on the surface of the workpiece more uniform,the shear force increases continuously,and the material removal rate is improved.With the increasing of abrasive diameter,the shear force decreases,and the material removal rate falls.The increase in the polishing slurry’s abrasive concentration reduces the workpiece’s pressure,and increases the shear force,and improves the material removal rate.Still,the concentration is too large to reduce the surface quality of the workpiece.