# Superhydrophobic Coating Solutions for Deicing Control in Aircraft
## 1 Introduction  
The term deicing involves actions and procedures aimed to remove or clear ice after formation on critical structures in the environment, while anti-icing systems are instead intended to prevent ice growth and deposition. The aviation industry is strongly affected by this phenomenon reflected in both technological and safety issues. Before aircraft take off, ice formation prevention procedures usually imply that anti and deicing fluids are commonly administered, even if their effectiveness diminishes rapidly as the aircraft accelerates [1] in addition to releasing harmful fluid components to the environment while, during flight, aircraft can employ heaters and inflatable guards to shield against ice. Physical parameters like wettability, temperature or pressure describe the direct response of materials to environmental conditions. The development of an anti-icing surface on a specific industrial coating patch or object has posed a persistent challenge for various industries, including aviation and wind power. To address this challenge, it is essential to perform surface modifications to incorporate the icephobic property into existing commercial coatings for practical applications. Additionally, permanent hydrophobic coatings can decrease the ability of water to adhere to the aluminum surface, preventing freezing. However, it has been demonstrated in [2] that these coatings can also compromise the effectiveness of anti-icing fluids. According to a recent examination carried out by scientists from Canada, there is a possibility that the application of anti-icing fluid alongside hydrophobic coatings may hinder the formation of a protective film. Researchers at Skoltech [3] also conducted experiments toassess the ability of aluminum surfaces used in aircraft skins to repel water and ascertain whether this has any impact on the effectiveness of these fluids. Nevertheless, we can regard SH or icephobic coatings (PIPS) as an adjuvant in the inhibition of ice formation during the take-off, in fact eliminating or strongly reducing the use of fluids or chemicals which, in turn, could result as harmful to the environment. The endurance of three distinct fluid types, all of which met the rigorous aerospace standards of SAE AMS1424 or AMS1428, was examined. These fluid types exhibited varying durations of endurance. To prepare for testing, aluminum plates underwent a process of sanding, polishing, and coating with a hydrophilic acrylic varnish, which yielded a transparent finish that could be either glossy or matte. The results of the Canadian team's study differ from those of the researchers, as they found that the wetting ability of plates did not affect the effectiveness of anti-icing fluids. However, the researchers attribute this divergence to the surface tension and viscosity of the fluids. Additionally, the researchers acknowledged that surface roughness (Sa) may be a factor, as it takes longer for ice to accumulate on rough surfaces. Also, temperature and pressure have been demonstrated to affect the shape of the supercooled water on the new icephobic coating. Mechanical tests like cutting, tape tests, pull-off tests and nanoindentation were carried out in [4] to assess the high durability of the icephobic coating. To claim that an icephobic surface is suitable for aeronautical application, it should be tested under flight conditions. This test is possible in an icing wind tunnel (IWT) that can mimic the icing or frosting process in the natural environment by spraying supercooled water droplets onto the substrates. Unfortunately, this facility is rather rare due to the high cost of the setup. In [5] the effects on roughness at the micro/nanoscale by the pressure have been evidenced due to the impinging of supercooled water droplets, in fact, the pressures at water droplet impact can reach up to \(10^{5}\) Pa with the strong mechanical wearing of the coating during its application.