Wetting Properties of Aluminium Surface Structures Fabricated Using Direct Laser Interference Patterning with Picosecond and Femtosecond Pulses

In this work, we report about the fabrication of textured aluminium surfaces using Direct Laser Interference Patterning with picosecond (70 ps) and femtosecond (400 fs) laser pulses as well as their wetting properties. The structuring process was performed by varying the pulse numbers from 25 to 250, resulting in various depths ranging from 0.9 [micro]m to 6.8 [micro]m. The wetting analysis shows that the ps-patterned surfaces exhibit long-term superhydrophobic characteristics (at 21 [degrees]C and 16 % air humidity). Differently, for the fs-processed substrates, a hydrophobic character was firstly observed, which later (after 16 days) dropped to contact angles similar as the untreated material. Keywords: direct laser interference patterning, picosecond, femtosecond, aluminium 2024, wettability, superhydrophobicity