Composite Technology Of Sapphire Chemical Mechanical Polishing And Thermal Field Control

Sapphire is widely used in military and civilian fields,but its high hardness and brittleness makes it difficult to process,resulting in low processing efficiency and prone to damage and defects on the surface.High-efficiency,high-quality,and high-precision machining is the key to ensuring the full performance of its parts and improving their life.In order to achieve high-efficiency,high-quality,and high-precision processing of single crystal sapphire,traditional chemical mechanical polishing has been difficult to meet its needs,and a new composite polishing technology needs to be developed.On this basis,it is proposed to use ultrasonic vibration to assist the energy field to improve the various indicators of chemical mechanical polishing.Finally,the lattice distortion layer facing the high-precision processing surface is repaired by thermal field to realize the rearrangement of surface atoms and improve the integrity of the lattice.Sapphire atomic-level step structure with uniformity.In this paper,molecular dynamics simulation is used to simulate the indentation and scratch process of sapphire,and the corresponding experimental research is carried out,and the anisotropy and processing methods are studied from the aspects of scratch load,surface morphology and subsurface defects.Influence.Ultrasonic-assisted chemical mechanical polishing experiments were carried out through molecular dynamics scratch simulation to improve the efficiency of traditional chemical mechanical polishing.Finally,the polished sapphire was annealed at high temperature to study the effect of heat treatment temperature on surface morphology and lattice integrity.（1）Carry out molecular dynamics indentation simulation on the three crystal planes A、C and M ofα-Al₂O₃crystal,and draw the relationship between elastic modulus and hardness and different crystal planes by Origin software.The corresponding nanoindentation test was carried out,and the hardness and elastic modulus parameters output by the nano-indenter were compared with the simulation results to verify the reliability of the simulation.Then,molecular dynamics nanoscratch simulation was conducted on C-plane sapphire using different processing methods.From the simulation results,it can be seen that introducing horizontal vibration can improve the atomic removal amount and introduce smaller damage during the scratch process,and the greater the amplitude,the better the effect.（2）Carry out ultrasonic-assisted chemical-mechanical polishing experiments on sapphire,and study the effects of ultrasonic amplitude,polishing pressure,and polishing speed on polishing efficiency and surface quality through single-factor and orthogonal experiments.The single factor test results show that the material removal rate increases with the increase of the polishing pressure.With the increase of the polishing disc speed,the material removal first increases and then decreases.When the polishing disc speed is75r/min When the ultrasonic amplitude increases,the material removal rate reaches a maximum value of 44.21nm/min.With the increase of the ultrasonic amplitude,the material removal rate also shows an increasing trend.Orthogonal test results show that when the polishing pressure is 54.06k Pa,the rotational speed of the polishing disc is60r/min,and the ultrasonic amplitude is 3μm,the maximum material removal rate is41.56nm/min,and the surface roughness of the sapphire sample is determined by the36nm before polishing becomes 0.47nm,and the surface quality has been greatly improved.（3）Perform high-temperature heat treatment on the polished sapphire sample to study the effect of different annealing temperatures on the surface morphology and lattice integrity.The results show that high temperature heat treatment can change the surface morphology of sapphire,and the surface of sapphire presents a long-range ordered nano-step structure at 1500℃.As the annealing temperature increases,the integrity of the sapphire lattice becomes better and the residual stress decreases.High temperature heat treatment can improve the surface quality of sapphire and reduce surface damage.The lattice integrity and residual stress are detected by X-ray diffractometer,and the surface morphology is observed by atomic force microscope,which provides a theoretical basis for high-efficiency and high-quality processing of sapphire.