Laser-induced selective wettability transition of 6061 aluminum alloy surfaces

Laser texturing enables site-selective tailoring of wetting characteristics of metallic surfaces, converting the surfaces into hydrophilic or hydrophobic ones. In this study, selective wettability transition of 6061 aluminum alloy (Al 6061) surface is demonstrated by using a nanosecond fiber laser. The conversion of initial wettability of pristine Al 6061 into a near-superhydrophobic surface is achieved through laser irradiation of an Al 6061 plate and the following low-temperature thermal annealing. The wettability change is studied by measuring the water contact angle, and a significant increase in the angle (approximately, from 63.9° of pristine Al 6061 to 146.8°) is observed. Furthermore, the laser-textured hydrophobic surface is transformed into a hydrophilic surface by irradiating the surface again with the laser beam, resulting in superwetting ability. These wettability transitions are site-selectively obtained by exploiting the capability of direct laser writing, showcasing a promising potential in various applications.