Role of micrometric roughness on anti-ice properties and durability of hierarchical super-hydrophobic aluminum surfaces

Ice accretion and accumulation may cause a severe problem in many disparate fields from aircraft to electrical transmission lines. Super-hydrophobic (SHP) surfaces can have a potential anti-icing application due to their extreme water repellency. However, there is a lack in the characterization of icing behavior of these surfaces. Moreover, durability is a major concern for this kind of coatings. One class of super-hydrophobic surfaces is constituted by hierarchical structures, in which a micrometric roughness is combined with a nanometric roughness and finally covered by a low energy chemical finishing. In the present work, we experimentally investigated how the micrometric roughness of the aluminum alloy surface can influence the hierarchical micro-nanostructure and the consequent hydrophobic and anti-icing properties, especially in terms of durability. Aluminum alloy samples were sandblasted or polished to generate a different micrometric roughness. The following steps to obtain a hierarchical super-hydrophobic structure (nano-roughness and final low energy chemical treatment) were kept constant for all samples. The hydrophobic properties were characterized at room and low temperatures and the anti-icing behavior was measured by shear stress tests. Several repetitions of the shear stress measurement on the same samples and icing- thaw cycles were conducted to study the durability of the coatings. This work describes an easy, fast and economic process to obtain super-hydrophobic materials with durable anti-icing properties, with interesting applications in many industrial fields.