Study on multiple liquid film-assisted laser shock waves cleaning of fluorinated ethylene propylene coatings on 6061-T6 aluminum alloy surface

Abstract

For the problem of local periodic removal and recoating of fluorinated ethylene propylene (FEP) coating on surface-resin transfer moulding (Surface-RTM) mold surface, this paper proposes the liquid film-assisted laser shock wave cleaning (LFA-LSC) technology, and analyzes the effects of the number of LFA-LSC on the surface cleaning effect, macroscopic/microcosmic morphology, elemental distribution, functional groups, and wettability of 6061-T6 aluminum alloy surface. It is shown that LFA-LSC can effectively remove the FEP coating on the surface of 6061-T6 aluminum alloy through the synergistic mechanism of thermal ablation, elastic–plastic deformation of the substrate, cavitation collapse, and plasma shock wave, and regulate the surface morphology and wettability of the substrate. The oxide film on the substrate surface undergoes the evolution of pore structure formation (1–2 times), pore density reduction (3 times), and film cracking (4 times). With the increase of the number of LFA-LSC, the coating removal increased first and then decreased, and the contact angle decreased first and then increased. When the number of LFA-LSC is 3, the coating removal rate is the highest (90.33%), the hydrophilicity is optimal, and the contact angle decreases from 67.3° to 35.6°, a decrease of 47.1%, which is conducive to the improvement of the interfacial bonding strength of the coating.