| QIN Zhe,GAO Qian,WANG Bin,YANG Ya-ting,CHEN Ya-jun.Technology and Mechanism of Nanosecond Pulse Laser Paint Removal of Aircraft Skin[J],51(7):370-376, 396 |
| Technology and Mechanism of Nanosecond Pulse Laser Paint Removal of Aircraft Skin |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.07.037 |
| KeyWord:nanosecond pulsed laser paint removal orthogonal test method surface morphology residual paint rate process parameters optimization |
| Author | Institution |
| QIN Zhe |
Sino-European Institute of Aviation Engineering, Civil Aviation University of China, Tianjin , China;Tianjin Liangyi Technology Co., Ltd., Tianjin , China |
| GAO Qian |
Sino-European Institute of Aviation Engineering, Civil Aviation University of China, Tianjin , China |
| WANG Bin |
College of Artificial Intelligence, Nankai University, Tianjin , China |
| YANG Ya-ting |
Sino-European Institute of Aviation Engineering, Civil Aviation University of China, Tianjin , China |
| CHEN Ya-jun |
Sino-European Institute of Aviation Engineering, Civil Aviation University of China, Tianjin , China |
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| Abstract: |
| Researches on laser paint removal mainly focus on the influence of laser energy density, scanning speed, pulse frequency and scanning times on paint removal effect and substrate performance. Although the best paint removal parameters are finally determined, there are some contingencies in the selection of paint removal research parameters. Orthogonal test method is a design method to study multi-factor and multi-level. It selects some representative level combinations from the comprehensive experiment according to Galois theory, and analyzes the results to find out the optimal level combination. In this study, a fiber pulse laser with a wavelength of 1 064 nm was used to remove about 35 μm thick epoxy paint on the surface of 2024 aluminum alloy substrate, which is commonly used in aircraft skin. The optimum process parameters of nanosecond pulse laser removal of epoxy paint on 2024 aviation aluminum alloy substrate were scientifically analyzed and found by orthogonal test. The micro morphology and residual paint rate of the sample surface after paint removal were analyzed by changing the parameters such as laser power, pulse frequency and scanning speed, combined with three-dimensional profilometer and scanning electron microscope. At the same time, in order to study the mechanism of laser paint removal, the composition changes of epoxy paint layer before and after paint removal were analyzed by energy spectrometer and Raman spectrometer. It is found that the main order of the influence of laser paint removal process parameters on the residual paint rate after paint removal is:scanning speed, laser power and then pulse frequency. The effect of scanning speed on the residual paint rate is obvious. When the scanning speed is low, the energy accumulation effect of pulsed laser is more obvious, the temperature of paint layer increases rapidly under the action of laser, and the high-temperature ablation effect of paint layer due to laser absorption increases gradually. When the scanning speed is high, the ablation effect is weakened, but due to the different coefficient of thermal expansion between the paint layer and the substrate, thermal stress is generated between them, resulting in the paint layer bouncing off the substrate due to thermal vibration. Taking the residual paint rate as the optimization index, the best combination of paint removal process parameters is obtained as follows:scanning speed of 60 mm/s, laser power of 7 W and pulse frequency of 20 kHz. The average value of residual paint rate on the surface of the sample is 0.02. By selecting appropriate process parameters, nanosecond pulse laser can effectively remove the epoxy coating on the surface of aluminum alloy matrix without damaging the matrix. The paint removal mechanism is mainly laser ablation effect and thermal vibration effect. By comparing the Raman spectra before and after paint removal, it is found that the Raman characteristic peaks of most functional groups in the components of epoxy paint disappear, and there are only weak carbide characteristic peaks. After laser ablation, a large number of carbides are formed in the epoxy paint layer on the sample surface. After the secondary carbon removal treatment, the carbides are basically removed by the effect of laser thermal vibration. This study can provide a reference for the determination of paint removal process parameters of aircraft skin in the future. |
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