Study On Laser Polishing Mechanism And Technology Of 6H Silicon Carbide Monocrystal And YBCO Superconducting Film

Laser polishing,as a new special processing technology,has a wide range of applications in many fields,especially when the traditional processing technology is difficult to process the special kinds of surface,micro-size fields and so on.Silicon carbide material is a very excellent semiconductor material,using in space and aerospace technology,and is difficult to replace the important position of SiC crystal.Yttri?m bari?m copper oxide high temperature superconducting material is the first discovered high temperature superconducting material.It has an extreme high superconducting transition temperature,which is wide used in magnetic levitation technology.In this paper,the laser micro-field laser polishing of 6H silicon carbide single crystal was carried out by excimer laser with a wavelength of 248 nm.The surface roughness before and after polishing was measured by using a three-dimensional surface profiler.The influence of laser energy density and beam spot overlap rate on the surface roughness of silicon carbide was analyzed by using the microstructure analyze of the crystal surface before and after polishing.The surface morphology of the laser polished crystal was observed by scanning electron microscopy,and the surface composition of the processed crystal was measured by laser Raman spectroscopy.The removal mechanism of the material during laser polishing was analyzed.At the same time,the ideal processing parameters are obtained,that is,the laser pulse energy is 320 m J-340 m J(0.314J/cm2),the repetition frequency is 4 Hz,the focal plane is 2.6 mm above,the laser polishing effect is the best and the sample surface roughness decreases about 80%.The excimer laser polishing of the silicon carbide monocrystal process is a complex mixture of physical and photo-chemical reactions.At the same time,the surface of YBCO high temperature superconducting thin film was polished through laser micro region polishing method by Kr F excimer laser with a wavelength of 248 nm.The effects of laser energy density,beam spot overlap rate and other factors on the surface roughness of YBCO superconducting thin films were analyzed by the microstructure characteristics of the material surface before and after polishing.The Raman spectroscopy of the polished samples were analyzed,and the removal mechanism of the YBCO crystal was determined by the excimer laser polishing,and the ideal process parameters were obtained.The process of excimer laser polishing is very complicated.For different materials,the selected process parameters and equipment are not the same.In general,the thermal effect of the excimer laser polishing material is small,and the surface roughness of the material after polishing is very low,which is a very feasible microregion polishing repairing method.