We have developed a simple protocol for producing superhydrophobic surfaces with improved structural resistance and durability. The surface of metals and alloys were chemically etched to induce an appropriate surface roughness, and then chemically modified with a self-assembled monolayer of an alkane thiol, to reduce the intrinsic surface wettability. Surface roughness and low surface energy are key requirements for superhydrophobic behaviour. Our superhydrophobic surfaces display water contact angles of about 165° and, at the same time, a hysteresis lower than 2°. These values are superior to those reported previously on metallic superhydrophobic surfaces.

Metallographic analysis showed a strong influence of the chemical composition and grain distribution on the topography developed during etching. Etching conditions were manipulated to achieve the surface roughness required for superhydrophobic behaviour. The evolution of the surface topography was monitored by optical microscopy and revealed dramatic differences between the metal and the alloy, which both exhibited superhydrophobic behaviour. Scanning electron and holographic microscopy as well as and laser and stylus profilometry were used to characterise the topography of the superhydrophobic surfaces.