Laser Ablation of Metal Substrates for Super-hydrophobic Effect

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 (R a ) 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.