Fishbone-like micro-textured surface for unidirectional spreading of droplets and lubricity improvement

Directional spreading of droplets on asymmetrical micro-structures surface has attract interests of researchers for its significant application potential in scientific and engineering fields. In this paper, a fishbone-like micro-textured surface (FMS) is proposed, which exhibits efficient unidirectional spreading behavior of droplets (maximum forward-backward spreading coefficient up to 3.7). The effect of geometrical characters on spreading performance are studied, thus facilitating obtainment of optimal parameters of the FMS. Such type of micro-structured surface is arranged on noncontact areas of pin-on-disk tribological system. Experimental results demonstrate the FMS has lubrication retention effect, resulting in reduction of friction and wear. The maximum reduction rate of friction coefficient is 63.3 % compared with the bare specimen.