Evaluation of laser cleaning for defouling of marine biofilm contamination on aluminum alloys

The environmental friendliness short-pulsed laser removal of marine biofilm contamination developed on the surfaces of aluminum alloy substrates was innovatively applied. Natural biofilms were formed using a seawater immersion method. The surface state was evaluated by considering the cleaning effectiveness and the harm exerted on the aluminum alloy substrate surfaces. The cleaning quality was analyzed using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), and Fourier transform infrared spectroscopy (FT-IR). The laser-induced damage/change to the substrate surface was evaluated using laser scanning confocal microscopy (LSCM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The results indicate that a nanosecond laser can be successfully used to quickly remove marine biofilm contamination from the surface of an aluminum substrate by instantaneous thermal ablation. No clear thermal damage can be found on the laser-cleaned aluminum surface at a lower laser fluence (1.08 J/cm²). In addition to the cleaning of marine biofilm contamination, a higher laser fluence (4.14 J/cm²) can also contribute to the formation of a hierarchical micro- and nanostructured oxidized layer. It is composed of amorphous-nanocrystalline phases.