Analysis of surface roughness of fluorocarbon aluminum powder coating during laser cleaning and its influence on laser absorption

In the process of laser cleaning the paint layer on the surface of 2024 aluminum alloy aircraft skin, the formation and evolution of rough surfaces can significantly affect the thermal interaction between the paint layer and the laser, as well as the removal mechanism. This study analyzed the changes in surface morphology and roughness of the paint layer during the layer-by-layer removal process using a 1064 nm pulsed laser. It investigated the generation mechanism and evolution pattern of rough surfaces, and calculated the effect of the rough surface of the paint layer on the laser absorption rate during the layer-by-layer removal process by establishing an equivalent analysis model for the rough surface of the paint layer. The results show that, rough surfaces appear on the paint layer after different removal mechanisms during the laser paint removal process, and there is a certain pattern in the evolution of rough surfaces during the layer-by-layer laser paint removal process;during the laser layer-by-layer paint removal process, the rough surfaces significantly increase the laser absorption rate, with an increase of 32.8% in the laser absorption rate after 7 laser treatments. If a fixed initial laser cleaning process is used, the increased absorption rate will lead to damage to the aluminum alloy substrate.