Research On Functional Microholes And Wettability Surface Fabricated By Ultrafast Laser Ablation

High-temperature alloy materials,gradient heterogeneous materials,ceramic-based new composite materials,and new-generation materials,such as silicon carbide and gallium nitride are widely used in aerospace,electronic information,and auto new energy fields.Owing to the extremely manufacturing requirements for functional microstructures,such as drilling,cutting and ablation,relevant manufacturing technology play an important role to the industry.Especially for high-efficiency and high-quality processing requirements,such as micro-holes,massive groups of holes,and surface micro-nano textures,traditional processing methods are more difficult to deal with these tasks.The ultrafast laser manufacturing technology is attracting more and more attention by academic community and industry because of its advantages such as minimal thermal influence and thermal stress,and no material restrictions.Many scholars have carried out related theoretical and application research.However,the physical phenomena of the ultrafast laser ablation for functionalized microstructures are complex,and the multiphase coupling mechanism of the light-thermal transferring and the joint adjust and control mechanism of the laser multi-parameters for the forming quality are not completely clear.Therefore,this paper systematically carries out the research of the fabrication technology based on the theoreticy of the interaction of light and matter,the digital control of laser ablation technology,and the processing mechanism of surface performance control.According to the fabrication requirement of functionalized micro-hole structures by ultrafast laser,the helical beam scanning technology has been established based on optical wedge rotation in this paper.The scanning control model of plate type helical beam has been put forward,and the method of photon path planning for helical beam scanning has also been explored.Meanwhile,the cooperative control mechanism of the deflector optical wedge and the displacement optical wedge has been established to realize the synchronous rotation control at high speed.Theoretical research of light-heat transferring has been developed based on helical beam scanning technology.To build the model of solid heat transferring,the ablation processing and characters have been simulated.The feasible gas-liquid-solid multiphase energy-coupling model and mechanism have been established in this paper.The influence mechanism of micro-hole processing has been studied and verified based on different power,scanning speeds,ablative path and defocus amounts by simulation and experiments.Through the study of femtosecond laser drilling process,the influence factors of laser energy distribution have been explored,and the forming mechanism of different type microholes based on femtosecond laser helical beam scanning has been clarified.The helical drilling process and technology have been developed and verified facing to alloy materials and hard brittle materials.Researched on helical scanning path planning,the laser power distribution,and defocus amount and other key parameters,the fabrication process and technology of controllable cone hole could be fulfilled by controlling the laser energy distribution and scanning path planning.To solve the problems of online measurement and closed-loop feedback control of functional micro-holes processing,one online vision measurement method based on edge feature detection and extraction has been applied to the fabrication of femtosecond laser processing.The general edge feature extraction method combined with dual-tree complex wavelet transform(DTCWT)and the Gini coefficient have been presented,and oriented to the key parameters measurement requirements for aero-engine air film cooling hole,online visual measurement method has been put forward to the femtosecond laser drilling,and also has been verified by experiment.However,due to the limitation of visual imaging,this method cannot fully monitor the laser processing of deep micro-holes,and it is necessary to realize closed-loop feedback process control combined with other detection methods.Finally,the periodic micro-hole channel structure has been fabricated by femtosecond laser is to realize the pattern liquid transferring by photo-thermal conditions.By analyzing the relationship between the wettability surface and the micro-holes on the zinc material plate,the wettability transformation of the pattern was realized by ultraviolet light irradiation,and the method of heating the liquid to reduce the surface tension of the droplet was applied.Finally,the rapid transferring of the modeled droplet was realized by using the micro-holes as micro-channels.It is further explained that the wettability change is caused by the change of pressure difference between liquid and zinc surface.It is clear that the abundant periodic micro-nano structure is an important factor for the wettability control of micro-hole surface,and the dynamic regulation mechanism of the periodic micro-porous channel structure and wettability surface has been explored.Oriented to fulfill the key process,and develop core component technology,and fabricat functional microstructures,application tests and verification of various materials and processing have been carried out in this paper,and the multi-directional and comprehensive systematic analyse and research in the field of application expansion of functional microstructures have been presented and illustrated.The above research will play a positive role in promoting the further research and application of ultrafast laser in the field of ultra-precision manufacturing technology.