Fabrication of micro-textured surfaces using ball-end micromilling for wettability enhancement of Ti-6Al-4V

The present work applied a high speed ball-end micromilling process for fabrication of micro-textured surfaces with different configurations such as parallel micro-dimple, staggered micro-dimple and micro grid, in order to enhance the wettability of Ti-6Al-4V. Advancing and receding angles of both untextured and micro-textured surfaces were measured using nano-scale ultrapure deionized water droplet. These angles were further utilized to predict Young's equilibrium contact angles to compare the wettability among different surfaces. Effects of different configurations, geometry variations (pitch, depth and diameter) and machining zone overlapping on equilibrium contact angle were investigated. Results indicate that all configurations of micro-textures enhance the wettability due to increase of roughness factor and area surface roughness. Further, machining zone overlapping influences the surface topography of micro-textures and plays a vital role in wettability enhancement. Among different configurations, micro grid texture with low pitch and high depth produces best wettability due to higher overlapping of the machining zone which produces unique pyramidal surface configuration. The pyramidal structure provides ease in droplet flow by providing larger interface area to occupy same drop volume that has also been confirmed by the drop shape analysis (drop radius and height). Further, stable contact angles were observed over time as chemical composition remained unchanged before and after micro-texture fabrication using ball-end micromilling.