Production of Super-Hydrophobic Al2024-T3 Surfaces by Using Nanosecond Fiber Laser

Aluminum alloy 2024 is the most widely used metal alloy in aircraft due to its superior characteristics. Although the effects of surface chemistry and topography on the wettability transition have been investigated in the literature, it has not yet been clarified which mechanism is more dominant. In this study, the super-hydrophobic Al2024 sample surfaces were obtained over time in a single step using a nanosecond pulsed fiber laser. Different micro- and nano-structures were produced by changing the laser output power and scanning speed. The effects of laser parameters on the wettability of the Al2024 samples were examined. As with the untreated sample, all fresh laser-treated samples have a hydrophilic or super-hydrophilic surface property. It was found that the fresh laser-treated aluminum alloy surfaces were super-hydrophilic. Then, the Al2024 samples were exposed to ambient air for a certain period. It was found that the contact angles (CAs) of all laser-treated Al2024 samples increased over time. Also, the water drop moved away from the surface of some super-hydrophobic samples at angles of less than 10 degrees. With more than 150 degrees water contact angle and less than 10 degrees sliding angle, it was proved that the lotus effect was obtained at various time scales. The icing properties of the lotus sample were investigated. The surface icing characteristics of the lotus sample have been improved. The XPS high resolution analyses show that the Al-C bond could be responsible for the wettability transition of the laser-ablated samples from hydrophilic to super-hydrophobicity (lotus). [GRPAHICS].

Automated summary

In this study, super-hydrophobic Al2024 sample surfaces were achieved using a nanosecond pulsed fiber laser. It was found that the fresh laser-treated aluminum alloy surfaces were super-hydrophilic, but the contact angles increased over time. The lotus effect was obtained at various time scales, with contact angles exceeding 150 degrees and sliding angles less than 10 degrees. The wettability transition from hydrophilic to super-hydrophobicity (lotus) was attributed to the Al-C bond.