Laser direct writing of rose petal biomimetic micro-bulge structure to realize superhydrophobicity and large slip length

Abstract

Large slip length at the solid-liquid interface is key factor in the performance of hydrostatic bearings. A superhydrophobic biomimetic-structured surface enables the surface with partial slip. Inspired by rose petal micron papillae, a superhydrophobic surface with biomimetic micro-bulge structures was fabricated by laser direct writing. The prepared surface of tin-bronze alloy shows superhydrophobic property, the maximum water contact angle (WCA) was 163°. The structured surfaces exhibited slip lengths of 20 µm and 37 µm for deionized water and VG5 lubricant, and the original smooth surface has no-slip. The slip length increases with the height of the micro-bulge and the viscosity of working fluid, a maximum slip length measured was 165 µm. It was found that the layered structure contributed to the increase in slip length, demonstrating the good drag reduction properties of the prepared superhydrophobic/oleophobic layer surface. This simple and inexpensive method can fabricate superhydrophobic surfaces with large-slip length, which applied to the solid-liquid interface of hydrostatic bearings can improve dynamic and static properties.