Superhydrophobic TC4 alloy surface fabricated by laser micro-scanning to reduce adhesion and drag resistance

Abstract

Surface drag resistance would cause energy waste in transportation industrials and vascular stenosis in biomedicine field, which is still an urgent problem to be solved. Selecting widely used Ti-6Al-4V (TC4) alloy as research object, the grid-shape micro-nano structure was fabricated on the surface by laser micro-scanning, and the superhydrophobicity with low adhesion was achieved after further chemically modified to lower the surface free energy. The change of the wettability in this process indicated that the superhydrophobicity was ascribed to a combination of the micro-nano structure and chemical composition. The bounce behavior was analyzed by obtaining the trajectory of water droplet via image processing, and the rebound coefficient was maintained at about 0.85, which fully verified the superhydrophobicity. The prepared superhydrophobic surface shows enough stability after the abrasion tests, soaking tests, and water impinge tests. The slip length, which indicates the drag reduction capability, was measured based on torque measurements with various shear rates. The prepared superhydrophobic TC4 alloy surface reduced drag effectively, yielding slip lengths of 17 μm with pure water and 40 μm with 30% glycerin-water solution, respectively. It is worth believing that this laser-based method would show great application potential in the fields of transportation and biomedicine, necessary condition to achieving superhydrophobicity.