Influence of microstructure on surface wettability

Wettability is one of the important performance measuring the hydrophobicity of metal surface. There has important relationship between microstructures and surface wettability. In this paper, square pillar microarrays with different geometrical parameters were processed on hydrophilic metal substrates by high-speed micro-milling technology, observed superficial morphologies and apparent contact angles of microstructures, and analyzed the influencing laws of geometrical parameters on surface wettability. Experimental results showed that the wetting transition from hydrophilicity state to hydrophobicity state was successfully achieved by fabricating micron-grade regular array on aluminum alloy surface, and the hydrophobic property on solid surface is a common coupling results of micronano-binary structures both microscale pillars and nanoscale pits and convexities. In this experiment, a good hydrophobic surface with larger apparent contact angle can be obtained when pillar width is 20 μm, pillar spacing is 100 μm, pillar height is 50 μm and the droplet volume is 3 μl. In addition, the water droplets on aluminum alloy surface with square pillar microarray is in a mixed state between Wenzel and Cassie-Baxter, and the surface wettability can be control by changing the geometry parameters of microstructures.