Laser cleaning has potential applications in the aviation field due to its environmental friendliness, flexibility, efficiency and adaptability. The CMS-CT-203 coating on the surface of C919 aircraft skin Al-Li alloy (2060) was cleaned by nanosecond pulse laser. The cleaning behavior of Al-Li alloy coating under different combinations of scanning speed, laser power, pulse frequency and scanning times was studied respectively. The removal depth and surface roughness were used as evaluation indexes for range analysis to explore the influence weight of each laser process parameter on different evaluation indexes. The laser process parameters of coating cleaning are orthogonally optimized. The characterization and mechanical properties of the specimens after cleaning under the optimal laser process parameters were analyzed. The results show that the factors influencing the cleaning effect, in order of weight, are scanning times > scanning speed, laser power > pulse frequency; the best combination of laser process parameters is scanning speed of 900 mm/s, laser power of 65 W, plus frequency of 140 kHz, scanning times of 4 times. The surface morphology of the original specimen is well maintained after laser cleaning. Additionally, it is also found that the hardness and tensile strength of the specimen surface after cleaning are slightly increased, maintaining the original mechanical properties of Al-Li alloy matrix. The complete removal of the surface coating of the Al-Li alloy is achieved without damaging the original mechanical properties of the substrate. This study provides a reference for the removal of aviation surface coatings.

Graphene nanoplatelets/aluminum (GNPs/Al) nanocomposites were fabricated using a novel two-step method. High resolution transmission electron microscope (HRTEM), Raman, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), EDS mapping, and mechanical testing system (MTS) were applied to characterize the microstructure and mechanical properties of the GNPs/Al nanocomposites. The GNPs were homogeneously dispersed in GNPs/Al nanocomposites, and presented a fine interface behavior and microstructure characteristics. A harmful phase, aluminum carbide (Al4C3), was not observed in significant quantities in the nanocomposite. Compared with pure aluminum, the mechanical properties of the GNPs/Al nanocomposites containing a low volume fraction of GNPs were sharply improved. When 0.5 vol.%, 1.0 vol.%, and 2.0 vol.% GNPs were added to the aluminum matrix, the average compressive strength of GNPs/Al nanocomposites was 297, 345, and 527 MPa, respectively, which remarkably increased the strength over the original aluminum by 330% to 586%.