Over the past decade, there has been growing interest in developing functional surfaces. Tuneable surface wetting properties have enabled the development of superhydrophobic and superhydrophilic surfaces, which repel or disperse water. These have resulted in self-cleaning, anti-fouling, and anti-corrosion technologies. Laser processing has shown to be effective in producing superhydrophobic and superhydrophilic surfaces, eliminating chemical requirements and providing cost-effective solutions. Although the laser treatments successfully achieved the desired extreme wetting and anti-corrosion properties, the long-term studies performed one month after their fabrication show ambiguous results and highlight the lack of long-term stability testing of these functionalities.

This study examines the functionality of laser-structured surfaces concerning their wettability properties and corrosion resistance over a two-year period following production. Two distinct laser techniques have been implemented to create line-like as well as random patterned surfaces Direct Laser Interference Patterning (DLIP) and Direct Laser Writing (DLW). Pulsed lasers sources (4-6 ns) with a wavelength of 1064 nm were used. The experiments yielded two distinct wettability states. The linear pattern yielded a superhydrophobic surface with water contact angles exceeding 150°, while the random pattern yielded a superhydrophilic surface with water contact angles below 10°. These characteristics remained stable throughout the 730-day observation period, as shown in Figure 1a. Potentiodynamic polarisation curves and electrochemical impedance spectroscopy (EIS) were used to evaluate corrosion behaviour. After 730 days, laser-treated samples had higher corrosion potential and lower corrosion current density (from 1026 nA·cm2 to 329 nA·cm2 for DLW and 390 nA·cm2 for DLIP). The EIS demonstrated an enhancement in polarisation resistance (Figure 1b). There are no significant changes observed in the corrosion behaviour of the surfaces after this long period of observation. The enhanced corrosion resistance observed in the laser-treated samples was attributed to the formation of a thicker oxide layer and a reduction in the concentration of Cu- and Mg- precipitates. In conclusion, the results of this study demonstrate the significant potential of laser-structured surfaces in achieving durable wettability properties and improved corrosion resistance, highlighting their potential for use in a range of applications.