飞秒激光在镍基合金上加工深宽比>20的直孔和倒锥孔  

Femtosecond Laser Processing of Straight and Inverted Tapered Holes with Aspect Ratio of>20 on Nickel⁃Based Alloy

作　　者：班铭霞 柴兆麟 王曼诗 张楠[1] 刘冰 Ban Mingxia;Chai Zhaolin;Wang Manshi;Zhang Nan;Liu Bing(Institute of Modern Optics,College of Electronic Information and Optical Engineering,Nankai University,Tianjin 300350,China;Rocket Force Characteristic Medical Center,Beijing 100088,China)

机构地区：[1]南开大学电子信息与光学工程学院现代光学研究所,天津300350 [2]火箭军特色医学中心,北京100088

出　　处：《中国激光》2024年第18期124-132,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(12374290)、开放项目(BEP21C003)。

摘　　要：镍基合金在高温环境下具有高强度、抗疲劳、抗蠕变和良好的耐腐蚀特性,是铸造航空发动机涡轮叶片的重要材料。下一代航空涡轮发动机的高进气温度(>2200℃)对叶片冷却效率提出了严苛的要求,直径≤100μm、深宽比>20的气膜冷却微孔是提升冷却效率的重要方案。提出了基于飞秒激光的旋转光束加工方法,在镍基合金上加工出直径约为100μm、深宽比>20的直孔和倒锥孔。此外,将偏振旋切方法与旋转光束方法结合,利用偏振旋切方法有效提升了直孔和倒锥孔的加工效率。Objective High-aspect-ratio microholes are widely used in the film cooling of turbine-engine blades.The development of nextgeneration aviation turbine engines with higher thrust-to-weight ratios is an important topic related to national strategic security,and improvements to the thrust-to-weight ratio and efficiency rely on the further optimization of the engine intake temperature.Currently,gas film-cooling technology uses cooling holes with a diameter of≥0.3 mm to form thermal protective gas films on the surface of hot components,and the cooling efficiency is typically less than 60%.The thrust-to-weight ratio of the next-generation aircraft engine can reach 15‒20,which corresponds to an intake temperature greater than 2200°C;thus,a cooling method that offers a higher cooling efficiency is necessitated.Studies show that film cooling holes with a diameter of~100μm and an aspect ratio of>20 can improve cooling efficiency significantly.Methods Laser spinning is adopted in this study to process straight and inverted tapered holes with a diameter of~100μm and an aspect ratio of>20 on Inconel 718 alloy.The combination of polarization trepanning and spinning beam machining improves the drilling efficiency of the straight and inverted tapered holes(Fig.1).A femtosecond-laser amplification system is used to output femtosecond-laser pulses with a center wavelength of 800 nm,a repetition rate of 500 Hz,a pulse width of 50 fs,and a maximum single pulse energy of 4 mJ.After passing through a tilted window and a half-wave plate,the femtosecond laser is focused onto the surface of the target material using a flat convex lens(L)with a focal length of 100 mm.The angle between the normal of the tilted window and the optical axis of the focusing lens is 15°.The target material used in the experiment is Inconel 718 alloy,with dimensions of 20.0 mm×20.0 mm×2.3 mm.The circular mask(aperture)at the exit of the laser amplifier is used to correct the crosssectional profile of the femtosecond laser.Results and Discussions Figure

关 键 词：飞秒激光加工 高深宽比直孔和倒锥孔 旋转光束加工方法 镍基合金 

分 类 号：V261.8[航空宇航科学与技术—航空宇航制造工程]