Laser cleaning has already appeared in the mid-20th century, but the research and application of this technology only gradually began in the late 20th century. For now, reports on laser cleaning are relatively common at home and abroad, and have become a hot research topic in the industrial field in recent years. The research content probably includes the theory, process, equipment, application, etc. of laser cleaning. Although the research related to laser cleaning is developing in a rich and diversified direction, due to the unbalanced relationship between development and research in various fields, there are still some problems that need to be solved and improved.

Research progress in laser cleaning of non-metallic composite materials

In 2016, relevant German researchers chose ultraviolet light with a pulse width of 28ns and a wavelength of 308nm to clean and remove grease from carbon fiber non-metallic composite materials. The laser power was 30W, cleaning efficiency is 9.6m2/h. In mass production and cleaning, a 600W laser can be selected, which is expected to achieve a cleaning efficiency of 58.3m2/h; Portuguese researchers studied the threshold of matrix phase fiber phase ablation under the action of femtosecond laser in 2017. By analyzing the threshold and incubation effects, it was concluded that epoxy resin can selectively remove some parameters during surface treatment. At the same time, by applying a laser with a wavelength of 1024nm and a pulse width of 550fs, the surface treatment of carbon fiber non-metallic composite materials can remove resin materials, change the surface roughness and morphology, and increase the area and bonding strength of the bonding material interface. In addition, by observing the interface of carbon fiber, you can also see the sub-micron corrugated morphology, which not only provides a bite point for process bonding, but also increases the bite effect. Therefore, in the process of choosing femtosecond laser to clean non-metallic composite materials, in addition to the cleaning and ablation effect, it can also perform surface micromachining of composite materials. This is the core advantage of using femtosecond laser for cleaning; Italian researchers In 2018, research was conducted on the surface impact of high-performance carbon fiber non-metallic composite materials in fiber laser cleaning. Carbon fibers were connected to polycarbonate through laser joining methods, and research work was carried out at the joints of epoxy resin. . The results show that the strength of the joint can be significantly improved through laser pretreatment, and under optimal conditions, the strength of the joint will be 2 times or more higher than that of the sample. At the same time, through the comparison of laser cleaning under different process parameters and the impact of laser treatment on joint strength, it was found that laser treatment can increase the apparent shear strength by more than 1 times; in 2017, relevant researchers in my country selected Use 50kHz infrared pulse laser to process carbon fiber non-metallic composite materials, and analyze the morphology under different combination parameters to study the effects of scanning speed and laser power on the morphology of the material surface. The results showed that contaminants and resin were removed from the material surface, and the laser cleaning parameters did not cause damage to the carbon fibers. At the same time, after laser treatment, the shear strength can reach a maximum of 27MPa. Compared with non-metallic materials without surface laser treatment, the shear strength has been improved by 36.15%; in 2018, relevant researchers from Donghua University in my country passed a comparison Before and after laser cleaning and mechanical polishing, it was found that the bonding strength of carbon fiber non-metallic composite materials with aluminum was improved by 195% compared with uncleaned and unpolished carbon fiber non-metallic composite materials. %, the bonding strength after polishing increased by 102%.

Application progress of laser cleaning of non-metallic composite materials

At present, in the aerospace field, laser cleaning is mainly used for the paint removal process of non-metallic composite materials. As far as the technology related to laser paint removal of non-metallic composite materials is concerned, foreign research has been earlier and has many successful cases. Our country is still in the exploratory stage. Although there are many excellent research results, the number is relatively small. The United States has conducted research on the effectiveness of paint removal technology in removing paint layers in non-metallic composite materials. The results show that through laser cleaning, the topcoat can be selectively removed while retaining the primer, and the topcoat and primer can also be removed at the same time. Primer not only has extremely high paint removal efficiency, but can also effectively save costs and time. Laser paint removal technology has been successfully applied to the surface of composite propeller blades of U.S. Navy helicopters, and the advanced laser coating and removal system developed by it has been successfully used in the paint removal ports of base fighters and cargo aircraft. Compared with previous paint removal methods system, this system and technology can save nearly 50% of paint removal time.

Conclusion

In summary, the application of laser processing can effectively solve the size, cutting, drilling and other problems faced by non-metallic composite materials in processing, thereby meeting the application needs of non-metallic composite materials in different fields and giving full play to their application advantages. At present, although the cutting, drilling, precision milling, cleaning and other related technologies in laser processing are not perfect, with the advancement of the times and the rapid development of laser processing, its related technologies and processes will be used in the processing of non-metal composite materials. Huge advantages, thereby effectively improving manufacturing efficiency, quality and precision, and providing a strong guarantee for the development of related industries.