近年来碳纤维复合材料(CFRP)由于性能优异, 受到工业领域广泛关注。 采用激光清洗技术预处理碳纤维复合材料表面的污染物和环氧树脂等杂质, 有利于改善碳纤维复合材料表面性能, 提高碳纤维复合材料胶接界面的结合强度。 在线检测激光清洗过程, 实时判断碳纤维复合材料的表面清洗质量, 是保证激光清洗效果的关键环节, 也是激光清洗装置自动化、 集成化的核心技术。 激光诱导等离子体光谱技术可以快速分析材料表面元素变化, 实现在线检测激光清洗表面状态, 在激光清洗领域有很广的应用前景。 采用Nd∶YAG高能量脉冲激光器产生的1 064 nm激光在空气环境中诱导产生等离子体, 利用改进型光栅光谱仪(ME5000)获取等离子体光谱, 在线检测激光清洗碳纤维复合材料。 研究外界空气环境对等离子体光谱检测结果的影响, 发现350~700 nm波段的元素谱线可用于碳纤维复合材料表面物质成分分析; 采用电子扫描显微镜观测的激光清洗表面形貌和X射线电子能谱仪测得的元素变化共同表征等离子体光谱检测的有效性, 通过采集不同激光能量以及不同作用次数的等离子体光谱图, 获得碳纤维复合材料表层树脂物质通过激光单次清洗干净的阈值, 研究激光清洗质量与激光诱导等离子体谱线成分及其强度变化的关系。 结果表明: 在获取的激光诱导等离子体光谱中, 光谱图中谱线波长在393.3 nm的S(Ⅱ)和589.5 nm的S(Ⅱ)谱线可有效在线表征碳纤维复合材料表面清洗质量; 激光单次去除干净表面环氧树脂的阈值为10.68 mJ; 低激光能量时需要清洗多次可以去除干净表面树脂; 高激光能量时清洗单次可使表面树脂去除干净, 多次清洗易造成基体损伤。 实验结果为激光清洗碳纤维复合材料的智能集成化应用提供工艺依据和技术支持。

In recent years, carbon fiber reinforced polymer (CFRP) has received extensive attention in the industrial field, due to its excellent performance. Laser cleaning technology for pretreatment of carbon fiber reinforced polymer is beneficial to the improvement of the surface properties and the bonding strength of the interface. The technology of detection assessment is the key to ensuring the quality of laser cleaning, and the core of the automation and the integration of laser cleaning device. Laser induced plasma spectroscopy can quickly analyze the changes of surface elements and realize the on-line detection of surface state of laser cleaning. It has a wide application prospect in the field of laser cleaning. In this paper, laser pulse which was produced by Nd:YAG pulse laser, with a wavelength of 1 064 nm,was used to induce plasma under the condition of room temperature and atmospheric pressure. Modified ME5000 grating spectrometer was used to collect the plasma spectrum. Laser induced plasma spectroscopy was used to detect the process of laser cleaning of carbon fiber reinforced polymer online. The plasma spectrum of air was obtained, and the influence of plasma spectrum was investigated. It was found that the spectrum of 350~700 nm can be used to analyze the surface composition of CFRP. The surface morphology observed by electron scanning microscope and the elements measured by X-ray electron spectroscopy were used to characterize the detection results of plasma spectrum. In order to obtain the threshold of removing the surface material completely of carbon fiber reinforced polymer, the plasma spectrograms under different laser energy and different cleaning times were collected. The relationship between laser cleaning quality and the main elements and their intensity changes of plasma spectrum were studied. The results showed that the 393.3 nm S (Ⅱ) and 589.5 nm S (Ⅱ) lines can effectively characterize the surface cleaning quality of carbon fiber reinforced polymer in the plasma spectrogram. The cleaning threshold of single laser to remove the surface material completely is 10.68 mJ. Low laser energy can remove epoxy resin more than once. High laser energy can remove the surface resin with single laser, but multiple cleaning will damage the carbon fiber. These results provide basis and technical support for the intelligent integrated application of laser cleaning carbon fiber composites.