Formation of sub-wavelength laser induced periodic surface structure and wettability transformation of CFRP laminates using ultra-fast laser

Abstract Present work focuses on wettability transformation of carbon fiber reinforced plastic (CFRP) surface by generating micro/nano-structures using a femtosecond laser system. Laser induced periodic surface structures (LIPSS) were realized on carbon fiber (CF) surface at different defocus distances and pulse energies. The hydrophilic CFRP surface obtained just after the laser treatment progressively depicts hydrophobic behavior and further transforming to near superhydrophobic after cleaning followed by vacuum process for 4 hours. Scanning electron microscopy (SEM) analysis was performed to capture the generated structure on the carbon fiber surface. Pulse fluence was effective parameters for transition of LSFL to HSFL. The lowest spatial period Λ ≈ 95 ± 6 nm and Λ ≈ 387 ± 15 nm was achieved for HSFL and LSFL, respectively, at 0.3 mJ.