Nanotextured Aluminum-Based Surfaces with Icephobic Properties

Undesirable water freezing (icing) usually occurs in cold environments and may have lethal consequences. Preventing icing usually requires the installation of active thermal systems which consume energy and increase costs. Nanoengineered superhydrophobic surfaces can delay freezing passively; however, when exposed to sub-zero temperatures, they can get covered by frost, which promotes ice formation and impairs their icephobicity. In addition, high thermal conductivity of the surfaces can reduce the frost formation rate. Thus, we chose aluminum as our working material for its good thermal conductivity and widespread industrial usage. We employed electrochemical anodization process to control and tune the surface morphology. Crucially, we demonstrate the feasibility of morphology control at the nanoscale and tunability of the surface solid fraction in the range of 0.1-0.25, while using safer polishing electrolytes and etchants compared to existing practice, i.e., our approach is environmentally friendlier. Surface functionalization and morphology control were used to render the surfaces (super) hydrophobic, with low contact angle hysteresis. The best performing surfaces demonstrate ice nucleation temperatures as low as -19 degrees C and resist liquid impalement-tested via drop impact velocity up to 3 m/s (Weber number > 300)-demonstrating a clear potential for their exploitation as icephobic surfaces.