| CVD diamond coatings deposited on the surface of carbide as a substrate have physical properties similar to those of diamond.The advantages of CVD diamond such as high hardness,high-temperature resistance,and strong cutting power have accelerated the research and development of CVD diamond coatings.However,reducing the surface roughness of the coating and optimizing its surface topography is an essential step in ensuring an effective bond between the CVD diamond coating particles and the carbide surface.With the continuous development of laser polishing material technology,although the individual laser polishing technology has the advantages of wide processable materials,low thermal influence,and low pollution coefficient,which can precisely solve the surface structure problem of CVD diamond coating and make polishing have a certain effect,the overall improvement effect is not very good and low efficiency.Using laser and ultrasonic compound polishing,the vibration performance of the ultrasonic vibration device can promote the uniform distribution of the processing surface melt and better improve the individual laser polishing effect,so the laser and ultrasonic compound polishing mechanism study of diamond coating is proposed,the main contents are as follows:(1)The research progress on polishing of CVD diamond coatings at home and abroad in recent years is summarised in four aspects: numerical calculation models for laser polishing of diamond coatings,polishing of diamond coatings by different laser types,the influence of laser-assisted devices on polished diamond coatings and the influence of different laser parameters on polished surfaces.(2)A brief description of the laser polishing mechanism,the CVD diamond coating and laser energy coupling mechanism,and the material removal mechanism are investigated,while the experimental device and ultrasonic vibration device structure design are established using 3D software.A theoretical model of diamond processing was developed in the simulation system,and a simulation model of CVD diamond polishing with laser and ultrasound was established to obtain a simulation of the change in temperature field with time.(3)Comparing the effects of different laser powers and scanning speed alone on the etching and polishing of coating samples and the composite polishing of laser and ultrasonic,then based on the summary of the comparative experiments,a Box-Behnken response surface analysis test was designed,and the prediction models of different analysis items were summarized and compared.Selecting the complete quadratic term forecasting model to analyze,through the results of variance analysis,the quadratic term regression equation is established.Then,the response surface was optimized to remove the insignificant items.The optimized model summary R-sq(prediction)increased by 3.3% compared with before optimization,and the model was still significant,and the quadratic regression equation was obtained.In the two-by-two interactive surface graphs,it can be seen that the entire surface of Ra is in a concave shape,indicating that the three laser parameters of laser power,scanning speed,and scanning distance have significant effects on Ra.Finally,for the optimized analysis,the laser power is 105.4545 m W,the scanning speed is 93.6364 mm/s,the scanning spacing is 28.8889 ?m,and the surface roughness is 0.2855 ?m,which is close to the lowest.Finally,the graphitization degree of the sample is detected by Raman spectroscopy,and a simple simulation verification is carried out.Figure [51] table [12] reference [84]... |
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