Laser ablation of metal substrates for super-hydrophobic effect

Abstract

Pulsed UV laser ablation is applied to fabricate super-hydrophobic surfaces on metal substrates. The spike shape micro-structure arrays achieved by the laser ablation on the brass substrates increase the surface roughness (Ra) from ~ 400 nm to ~ 5 μm. Meanwhile, plenty of nano-structures (200 ~ 600 nm) are also formed and scattered on the surface of the micro-structures. It is found that the water contact angle of the brass substrate increases from 110° to 161°. Super-hydrophobic property of the metal surfaces with both the micro- & nano-roughness is explained by water repellent model for double roughness structures. High speed camera imaging is used to analyze water droplet dynamics during its rolling down along the slanted super-hydrophobic brass surface. It shows that the pulsed laser ablation is a versatile approach to create large area super-hydrophobic surfaces for industrial applications.