Ice accumulation on conductors can lead to extensive mechanical damage and subsequent blackouts; heavy snowfall with high water content is the main cause of blackouts for Italian overhead lines. Modifying the wettability properties of aluminum can be a strategy to hinder snow sleeve formation and reduce ice adhesion.

In this work, different hydrophobic and super-hydrophobic surfaces were prepared on aluminum alloy samples by first generating a petal-shaped nanostructure, called pseudo-boehmite (Al(OOH)), through a hydrothermal process and finally coating the nanostructure with a fluorinated siloxane.

Several immersion times (1-150 min) in boiling water were tested, resulting in a boehmite layer with different nano-roughness and porosity levels. Oxide growth was observed with EDX and FTIR. The hydrophobic behavior of the samples was studied both at room temperature and at low temperatures (down to -10°C). For comparison, the Water Contact Angles (WCA) of the unboiled coated sample were also collected. All boiled samples showed higher WCAs than the unboiled sample, both at room temperature and at low temperatures. In some cases, very high WCAs were obtained, but the relationship between boiling time and hydrophobicity is not linear. Contact angle measurements were also performed at low temperatures: in this case, the WCAs of the samples decreased, while still maintaining good hydrophobic properties. The contact angle hysteresis and the roll-off data at room and low temperatures show a similar dependence on the processing time.

To evaluate the ice-phobic properties of the coatings, the ice-surface adhesion forces were measured through shear stress tests. Ice adhesion was lower in all boiled samples, showing an interesting nonlinear dependence on boiling time. Repeated shear stress tests provided measurements of the coating durability.