Experimental Study On Fabrication Of Single Crystal Diamond Microstructure By Femtosecond Laser Ablation

Diamond is widely used in precision optics,mechanical processing and electronic components due to its excellent properties of force,electricity,heat and light.Because of the high hardness and thermal stability of diamond,the diamond material has a series of difficult processing problems,such as low processing efficiency and large tool loss in the diamond material processing process,which greatly restricts the further application of diamond materials.However,traditional machining methods have poor processing quality and long processing cycles.Long pulsed lasers,due to their long pulse width and low power density,inevitably have energy accumulation,resulting in significant thermal damage during laser processing.Femtosecond laser can effectively overcome the heat effect of long pulse laser processing because of its very short pulse width and high single pulse energy,which has remarkable advantages for the precision machining of high melting point and super hard materials.In view of the above situation,A set of femtosecond laser processing test platforms was set up.A series of ablation tests were performed on single crystal diamonds.Formed ablative processing was made on the single crystal diamond,and a comparative wiping test of positive and negative rake single particles was performed.The detail description is listed as follows:(1)The difficulties in diamond processing and the characteristics and applications of femtosecond laser processing technology were mentioned,the research status of laser processing diamond materials and femtosecond laser processing was introduced.A set of femtosecond laser processing test platforms was set up.(2)Single-pulse and multi-pulse cumulative ablation threshold tests were designed to test the ablation threshold of monocrystalline diamond ablated by femtosecond lasers.The single pulse ablation threshold and multi-pulse cumulative ablation threshold of single crystal diamond were calculated by the method of straight line fitting.The variation rule of ablation threshold of single crystal diamond under multi-pulse was studied.(3)Based on single-variable experimental design,the effects of average laser power,spot overlap ratio,and number of scans on the surface quality,ablation depth and width of single crystal diamond ablation structures were investigated,and the optimal combination of femtosecond laser ablation parameters were obtained(The average laser power was 11.1 W,the spot overlap ratio was 61.9%,and the cycle scan number was 100),and a concave structure having a good surface quality was achieved on the single crystal diamond.(4)Through a laser layered forming ablation process,a positive rake structure is machined on the diamond abrasive grains,and a diamond grinding wheel with a positive rake angle is manufactured.A comparison test of single-particle positive and negative rake angles was carried out to compare the difference in the appearance of scratches produced by positive and negative rake angles,the difference in the surface morphology of the scratches was analyzed,and it was indirectly verified that the grinding force with a positive rake angle can significantly reduce the normal grinding force and improve the surface quality of the hard and brittle material.