Fig. 1. Composite paint layer on aluminum alloy surface

Fig. 2. Schematic of laser cleaning device

Fig. 3. Element content. (a) Top-coat; (b) primer; (c) anodic oxide film layer

Fig. 4. Two-dimensional morphologies of cleaned surface at different laser energy densities. (a) 1.78 J/cm²；(b) 2.11 J/cm²; (c) 2.67 J/cm²; (d) 3.11 J/cm²; (e) 3.56 J/cm²; (f) 4 J/cm²; (g) 4.45 J/cm²

Fig. 5. Three-dimensional morphologies of cleaned surface at different laser energy densities. (a) 1.78 J/cm²; (b) 2.11 J/cm²; (c) 2.67 J/cm²; (d) 3.11 J/cm²; (e) 3.56 J/cm²; (f) 4 J/cm²; (g) 4.45 J/cm²

Fig. 6. Two-dimensional morphologies of cleaned surface at different laser scanning speeds. (a) 10 mm/s; (b) 8 mm/s; (c) 6.5 mm/s; (d) 6 mm/s; (e) 5 mm/s; (f) 4 mm/s

Fig. 7. Three-dimensional morphologies of cleaned surface at different laser scanning speeds. (a) 10 mm/s; (b) 8 mm/s; (c) 6.5 mm/s; (d) 6 mm/s; (e) 5 mm/s; (f) 4 mm/s

Fig. 8. Effect of laser scanning speed on roughness of cleaned surface

Fig. 9. Cleaning effects under different parameter combinations. (a) 4 J/cm², 6.5 mm/s; (b) 3.56 J/cm², 6 mm/s

Fig. 10. Element distribution of cleaned surface and remaining thickness after cleaning with different parameter combinations

Fig. 11. SEM morphologies of anodic oxide film surface. (a) Original anodic oxide film; (b) anodic oxide film cleaned at parameter combination of 4.45 J/cm² and 5.5 mm/s; (c) anodic oxide film cleaned at parameter combination of 4 J/cm² and 5 mm/s; (d) anodic oxide film cleaned at parameter combination of 3.56 J/cm² and 4.5 mm/s

Fig. 12. EDS analysis of anodic oxide film cleaned at different parameter combinations. (a) 4.45 J/cm², 5.5 mm/s; (b) 4 J/cm², 5 mm/s; (c) 3.56 J/cm², 4.5 mm/s, position A; (d) 3.56 J/cm², 4.5 mm/s , position B