On the Corrosion Properties of Aluminum 2024 Laser-Textured Surfaces with Superhydrophilic and Superhydrophobic Wettability States

In this work, the mechanism of the corrosion behavior of laser-treated aluminum is studied. Two different laser techniques are used to fabricate the samples, direct laser interference patterning (DLIP) and direct laser writing (DLW), using nanosecond laser sources. The DLIP treatment uses a two-beam optical configuration producing line-like periodic structures. The DLW technique is employed to produce non-periodic structures on the Al-surface with the same cumulated fluences as in DLIP. The surface topography is analyzed by confocal microscopy, and the formation of oxide layers is investigated by scanning electron microscopy of cross-sections produced using a focused ion beam. Wetting measurements performed on the laser-treated samples exhibit a contrasting behavior, leading to either superhydrophobic or superhydrophilic states. In the case of the DLIP treatment, the static water contact angle is increased from 81 & DEG; up to 158 & DEG;, while for DLW, it decreases to 3 & DEG;. Electrochemical tests demonstrate a decreased corrosion rate after laser treatment. Additionally, findings indicate no correlation between wettability and corrosion reduction. Therefore, the improvement in corrosion resistance is mainly attributed to the oxide layer formed by laser treatment. Although similar corrosion rates are achieved for both treatments, surfaces produced with DLIP can be beneficial when additional surface properties are required. This study reveals how laser processing can be used to improve the corrosion resistance of aluminum by characterizing its corrosion behavior. It is demonstrated that laser treatment results in enhanced corrosion performance through the formation of a thicker oxide layer and that there is no correlation between corrosion resistance and superhydrophobicity. However, superhydrophobicity adds supplementary functionalities to the surface.image