Simulation And Experiment Research Of Vibration Assisted Electrochemical Polishing Silicon Carbide

Sintered silicon carbide has the characteristics of wearing resistance,excellent oxidation resistance,chemical corrosion resistance,high thermal conductivity and high heat resistance.However,the silicon carbide is ceramic material with high hardness,high brittleness,the defect sensitivity,poor anti-shock performance,which hinders the application of single crystal silicon carbide in high precision in space optical system.The current polishing methods have the disadvantages of poor machined surface or low material removal rate.Based on electrochemical polishing,vibration assisted electrochemical mechanical polishing is applied to improve the polishing efficiency and polishing quality.In this paper,the temperature field,flow field and electric field of vibration assisted electrochemical polishing single crystal silicon carbide are analyzed and studied to investigate the effects of different technological parameters and experimental conditions on the polishing results.It provides technical and theoretical basis for solving the problem of machining SiC mirror.The contact model between the silicon carbide specimen and the optical disk was established.The transient motion of horizontal reciprocating vibration aided polishing was modeled by COMSOL Multiphysics software and classical heat transfer theory.The parameters of frequency,amplitude,load and other variables were calculated and analyzed by means of parametric scanning analysis.The influence of each variable on the surface temperature distribution of the specimen and the optical disk was obtained.The flow field and electric field model of the processing area between the silicon carbide specimen and the polishing disk were established.The influence of frequency,amplitude and polishing pad on the flow field and the effect of polishing solution with different conductivities and applied electric field on the electric field in the polishing region were obtained by parametric scanning method.The design,manufacture,installation and debugging of the vibration aided electrochemical polishing machine were completed,and the relative sliding path between the test piece and the polishing disc was analyzed.The numerical control system can make the experiment table move in a circle translation,and the radius,speed and movement time of the circle translation could be set.The data acquisition system could collect,display and save the force and friction coefficients instantaneously.A series of polishing experiments were carried out by using a vibration assisted electrochemical polishing machine,and the effective experimental data was collected.By comparing the experimental data,the effects of the composition of the polishing solution,the vibration assistance and the applied electric field on the frictioncharacteristics and the material removal rate during polishing were obtained.