Nanostructuring of laser textured surface to achieve superhydrophobicity on engineering metal surface

Superhydrophobic metal alloy surfaces are increasingly employed in aerospace and naval applications for anti- icing, drag reduction, self-cleaning, and high-efficiency light absorption capabilities. Emerging laser-based surface texturing methods demonstrate significant potential for manufacturing these surfaces, with the advantages of high processing precision and flexibility. In this research, superhydrophobicity is achieved on engineering metal surfaces using a novel nanosecond Laser-based High-throughput Surface Nanostructuring (nHSN) process. First, a high-energy nanosecond pulse laser scans the metal surface submerged in water using a large spatial increment and a fast processing speed. After that, the laser-textured surface is further treated by immersion in a chlorosilane reagent for a specific period of time. As a result of these two processes, micro- and nano-scale surface features are generated on the metal surface. These features are measured on AISI 4130 steel workpieces through X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) and correlated with processing conditions. The features are also compared after completion of each process step to understand their individual and cumulative effect on the textured surface. It is found that utilizing a high laser power intensity during the laser texturing process phase will significantly enhance surface nanostructuring effects after the chlorosilane treatment, resulting in feature size decrease and increase in feature density.