Anisotropic hydrophobic surface fabricated by microstructuring of aluminum alloy using high speed micro-milling

This paper put the microstructures of rice leaf surface as bionic object, grating micro-arrays were processed on 7075 aluminum alloy surface by high speed micro-milling machining (HSMM). The micromorphologies and hydrophobic properties of specimen surfaces were studied adopting scanning electron microscopy and contact angle (CA) goniometer, and analyzing its hydrophobic mechanism. Results show that hydrophobic surfaces is successfully fabricated only by building grating micro-array structures on aluminum alloy surface using HSMM without modifying any chemical substances, the contact angle on aluminum alloy surface increased maximally to 152. 83° from 63.27° before processing. Furthermore, the contact angle on specimen surfaces appear anisotropic wettability, which the contact angle difference of two direction is about 40°~60°. In addition, the hydrophobicity and super-hydrophobicity on aluminum alloy surface is a coupling function result by both submillimetre regular grating arrays and many irregular nanoscale pits and projections distributing on submillimetre grooves surface.