Laser Patterning of TiAlN for the Creation of Surfaces with Selective, Anisotropic Wetting
摘要
TiAlN coated tungsten carbide is patterned by ultra-short laser pulses to create modified surface topographies. It turns out that this procedure is applicable to create structures both on the microscale (“large”) using a sophisticated beam guiding and on the submicron-scale (“small”) owing to the formation of surface modulations by intrinsic laser-TiAlN interaction (laser-induced periodic surface structures, LIPSS). The final goal is the preparation of surfaces with controlled interaction with polar and non-polar liquids. The presented work consists of two steps. First, the laser ablation process itself is studied to extract relevant irradiation parameters for a productive formation of the surface pattern. Second, the corresponding impact on the surface interaction of water and diiodomethane is studied. To separate the effect of “small” and “large” patterns, the LIPSS are created under a particular angle of 60°. Anisotropic drop shapes corresponding to the orientation of the lines are found that can be attributed to different surface topographies. The employed way of looking at the droplets is rather untypical for wetting studies, but indispensable to visualize the anisotropy of the droplet and a possible deflection along the LIPSS.