Investigation On Coating Of Nickel Alloy Surface By Femtosecond Laser Induced Forward Transfer

Femtosecond laser processing has become a new trend in material surface modification processing due to its short pulse time,high processing precision and small heat-affected zone.If femtosecond laser processing technology is used to modify the GH4169 high-temperature nickel-base alloy used in aero engines,the alloy can be widely used in the aerospace industry.In this paper,the surface of GH4169nickel-based alloy sample is processed by femtosecond laser directly induced ablation processing and femtosecond laser induced forward transfer method.The main research contents are as follows:Use electron beam evaporation equipment to find the best preparation conditions,control the evaporation time and beam size.NiCoCrAl-Y2O3 film and SiC film meeting the experimental requirements were prepared,and the approximate relationship between evaporation time and film thickness was found.The two films were analyzed by XRD diffraction.It was found that the source material was destroyed during the evaporation process due to the absorption of heat,resulting in a change from crystalline state to amorphous state.The surface of the nickel-base alloy sample was induced and ablated using a femtosecond laser processing equipment,and the ablation traces under different conditions were obtained by changing the laser power,laser scanning speed and laser defocus distance.The confocal microscope was used to observe the line width and morphology of the ablation traces,and the different effects of each variable were summarized.It was found that the nickel-base alloy samples gradually showed more severe ablation trace morphology as the absorbed energy of the sample surface increased.NiCoCrAl-Y₂O₃ film and SiC film were transferred to nickel-base alloy samples by laser induced forward transfer method.The effects of laser power,laser scanning speed,laser defocus distance on the deposition morphology,deposition line width and deposition amount were investigated.A good overlap of the laser spot is achieved by reducing the scanning speed or increasing the defocus distance to obtain a continuous and complete film deposition.In addition,the above experiments were repeated using a high-frequency femtosecond laser to analyze the effect of the increase in femtosecond laser frequency on the experimental results and the feasibility of applying high-frequency femtosecond lasers in laser induced ablation and laser induced forward transfer experiments.The foundation for future research is laid.