Critical surface characteristics for coating adhesion and friction behavior of aluminum alloys after laser cleaning

Coating adhesion and friction properties are critical for the utilization and maintenance of de-painted surfaces. This study utilized the "low-temperature processing" characteristic of ultraviolet picosecond lasers for the nondestructive removal of coatings on aluminum alloys, facilitating environmentally friendly paint stripping and subsequent applications. By adjusting laser fluence, surface morphology, chemical properties, and interface characteristics were evaluated, and temperature monitoring during the cleaning process was conducted to elucidate the cleaning mechanism. The results indicated that a laser fluence of 1.30 J/cm² is the threshold for complete coating removal. The fully stripped substrate exhibited surface roughening, slight oxidation, and polarization, which enhance wettability. This improved wettability, in turn, increases coating adhesion and wear resistance. Temperature monitoring results revealed a minimal photothermal effect during the ultraviolet picosecond laser cleaning process, ensuring the substrate remains intact. The de-painting mechanism primarily relies on the photochemical effect, enabling paint removal at low temperatures.