Study on nondestructive laser cleaning of aviation aluminum alloy surface coating

The laser cleaning has some advantages as non-pollution, safety and controllability, which has significant applications in aerospace, electronic field and transportation. The nanosecond pulsed laser was used to clean TB06-9 coating on the surface of aviation 2A12 aluminum alloy. A novel two-step nondestructive laser cleaning process was developed. Scanning electron microscope, energy dispersive spectrometer, ultra depth of field three-dimensional microscope and universal electronic testing machine are applied to investigate laser cleaning coating. The results show that, the first step is to use a laser cleaning, with the increase of the power, the coating on the sample surface decreases gradually, and the oxide layer and substrate are exposed. When the laser power is 40 W, the oxide layer is well preserved. When the laser power is increased to 45 W, the oxide layer begins to be damaged, with increase of the laser power, the damage of oxide layer gradually increased. The optimization parameters of the first step are the laser frequency of 20 kHz, power of 40 W, scanning speed of 1 040 mm/s and line spacing of 0.052 mm respectively. The second step is to carry out multiple cleaning based on the first step. The second parameters are laser frequency of 1000 kHz, power of 80 W, scanning speed of 690 mm/s, line spacing of 0.034 5 mm respectively. The surface morphology of sample by two-step laser cleanning samples is similar to that of the original samples, and the surface microhardness and tensile strength of the samples remain consistent. The mechanical properties of the material are well maintained.