Fabrication of Superhydrophobic, Permeable, and Anti-Reflective Porous Steel Surfaces using Laser Ablation and Heat Treatment for Multifunctional Applications

Abstract

Abstract Achieving high water resistance, good permeability, and anti-reflectivity on metal surfaces in a cost-effective and efficient manner has always been a major challenge. This study addresses these challenges by utilizing laser ablation and heat treatment to achieve high water resistance, breathability, and anti-reflection properties in porous steel. The laser ablation and heat treatment process generated a unique porous nested structure on the surface and imparted excellent hydrophobicity and low adhesion properties on the porous steel surface. The size and density of the porous nested structure can be adjusted by changing the laser parameters. Notably, hydrophobicity of the surface is demonstrated to be closely related to the complexity of the surface microstructure, which follows the same trend as the permeability and anti-reflectivity. Specifically, higher laser power and smaller laser spacing generate structures with greater aspect ratios and higher porosity, resulting in a rough surface with an increased air contact area and, consequently, an increase in the viscous permeability coefficient (B). Moreover, the intricate porous nested structure acts as a complex "light trap," whereby the reflectivity of the superhydrophobic porous steel surface ( laser power of 25.4 W and scanning interval of 100 µm) can be less than 15% across a wide wavelength range (200 nm-1800 nm). This study presents a method for fabricating multifunctional surfaces with superhydrophobicity, permeability and anti-reflectivity on permeable steel. The method provides an efficient and cost-effective solution to improve the performance of existing materials and has great potential for a wide range of applications such as solar cells, military stealth, and reduced navigation resistance.