Fabrication and characterization of superhydrophobic surface by electroplating regular rough micro-structures of metal nickel

The superhydrophobic behavior has attracted many researchers' attention. The conventional method of obtaining superhydrophobicity involves the combination of the coating of low-surface-energy material and constructing roughness on smooth surface. According to Cassie-Baxter law, this paper proposes a method that the superhydrophobicity could be obtained on structured hydrophilic surface without any coating of low-surface-energy material. Based on the surface micromachining technology, the superhydrophobic behavior has been achieved by the fabrication of micro-nickel cylinder array. It has been proved by the experiments that the micro-cylinder arrays exhibit superhydrophobic behavior: the maximum contact angle (CA) between the array and the water droplet can be up to 155 degrees, while the intrinsic CA of smooth nickel surface is 82 degrees. By controlling the parameters of cylinders (diameter/height/spacing), we investigated the relationship between the hydrophobicity and the above parameters. It proved that the spacing height ratio contributed to the transition from Cassie's model to Wenzel's, which was the main cause of disappearance of superhydrophobicity. (C) 2012 Elsevier B.V. All rights reserved.