碳纤维增强树脂基复合材料表面的紫外激光清洗微观形貌

Micromorphology studies of carbon fiber reinforced polymer surface cleaned by ultraviolet laser

胶接预处理是航空复合材料胶接中的重要工序,经过预处理的复合材料表面形貌将直接影响材料的胶接强度。本文基于复合材料紫外脉冲激光清洗技术,通过分析不同工艺参数组合下的材料表面激光清洗微观形貌,来探究紫外激光功率和扫描速度对碳纤维增强树脂基复合材料(Carbon Fiber Reinforced Polymer,CFRP)表面形貌的影响,并比较了经激光预处理和其他方法预处理的胶结试片的单搭接剪切强度。结果表明:当激光频率为60 kHz,扫描速度为300 mm/s时,随着激光功率的增大,CFRP板材表面和间隙的树脂均得到清除,当激光功率增大到8.5 W时,纤维间的树脂被完全清除,当激光功率为13.6 W时,表面树脂和纤维间的树脂均被完全清除;当激光频率为30 kHz,激光功率为13.6 W时,随着激光扫描速度的增大,表层的残留树脂增多,当激光扫描速度为500 mm/s时,碳纤维完整性良好,表层树脂分布均匀且纤维间树脂被完全清除。力学测试显示经适当的紫外激光清洗处理(激光频率为30 kHz,功率为13.6 W,扫描速度为500 mm/s)后,单搭接胶结试片性能可达到与可剥布处理相当的水平,且性能数据离散性(CV值)显著优化。

The adhesive bonding pretreatment is an important process in the aerospace composites bonding.The bonding strength of the material is affected by surface morphology of the pretreated composite material directly.Based on ultraviolet(UV)pulsed laser cleaning technique of composite material,the effects of UV laser power and scanning speed on carbon fiber reinforced polymer(CFRP)surface morphology were studied by analyzing the laser cleaning microstructure of material surface under different process parameters,and also,comparison were made between single lap shear strength of bonded coupons pretreated by laser with those by other methods.The results show that when the laser frequency is 60 kHz and the scanning speed is 300 mm/s,the CFRP surface resin and interstitial resin are removed with the increase of laser power.The resin in the interstices of fibers is cleaned completely by the UV laser with the power of 8.5 W.The resins on the surface and in the interstices of fibers are cleaned completely by the UV laser with the power of 13.6 W.When the laser frequency is 30 kHz and the laser power is 13.6 W,the surface residual resin increases with the rise of the laser scanning speed.When the laser scanning speed is 500 mm/s,the carbon fibers have good integrity,the surface resin distributes uniformly and the resin in the interstices of fibers is completely removed.Mechanical test results show that when the laser frequency is 30 kHz,the laser power is 13.6 W,and the scanning speed is 500 mm/s,single shear strength of bonded coupons treated by laser could reach a equal level of that treated by peel ply,with significantly optimized discrete values(CV values).