High speed micro-milling experiment of hydrophobic microstructure

This paper presents a method to fabricate the ordered arrays of microstructures on the metal surface using mechanical micro machining technology. With specific designed micro square pillar arrays, the wettability of a solid surface can be tuned. The samples were fabricated by high speed micromilling machine tool on the aluminum alloy surface. The apparent contact angle (CA) and microstructure of the surface were measured and the surface hydrophobic mechanism was also analysed. The results of the experiment indicate that the CA has been increased. The height-to-length ratio h_r (h/a) is one of the key parameters to change the wettability of the material surface. Compared with the intrinsic CA (about 51°), the largest apparent CA is up to 102.88° when the height-to-length ratio h_r (h/a) is 3/7. Furthermore, by controlling the size and layout of the micropillars, the aluminum alloy surface could be changed from hydrophilic to hydrophobic.