# Superhydrophobic Coating Solutions for Deicing Control in Aircraft
## 4 Deicing Fluids  
Regardless of whether innovative coatings investigated as potential passive ice protection systems were hydrophobic, superhydrophobic, or SLIPS, they must resist the effects due to the application of deicing fluids and simultaneously that the fluids do not lose effectiveness when applied to surfaces. The problem with deicing/anti-icing fluids regards their composition because they are mainly composed of water, glycols, additives, and surfactants with potential adsorption to the surface and consequential loss of their initial highly hydrophobic properties. [PERSON] et al. [2] performed two current test methods used to qualify the ground deicing/anti-icing fluids on five different surface coatings, commercial and under development, and the results were used to develop a section of the SAE AUR6232 about fluids endurance time. They found that, depending on used deicing/anti-icing fluids, some surfaces could reduce the fluid endurance time that was regulated by law (Figure 9). The authors found no direct correlation between the CA and the endurance time and even when a positive result was observed, it was possible that the surface affected the fluid flow off establishing possible negative effects on aerodynamics. A later study setting out to explore this problem is more accurately described in [3]. In this paper, as opposed to [2], the authors provided detailed information about commercial anti-ice fluids (density, viscosity and surface tension) and employed surfaces (Sa, advancing and receding CA). Superhydrophilic and hydrophobic surfaces were used to test the ice protection of three commercially anti-icing fluids during the water spray endurance test. It was observed that surface wettability had no effect on the anti-icing fluid endurance time and that the results of ice accretion and durability were correlated with fluid viscosity and surface tension. The authors in particular stressed how surface roughness was important and must be considered for comparative studies since rough surfaces took longer to accumulate ice due to the presence of anti-ice fluid in the surface texture.  
Figure 8: Graphs of ice adhesion tests after glaze and rime icing procedures in IWT. Reprinted with permission under the terms of the Creative Commons CC BY license from [PERSON]; [PERSON];[PERSON]; [PERSON]; [PERSON];[PERSON]; [PERSON] Icephobic and Anticorrosion Coatings Deposited by Electrospinning on Aluminum Alloys for Aerospace Applications. Polymers 2021, 13, 4164 [40].  
On the other hand, [PERSON] et al. [41] investigated the negative effects of deicing fluids on coating performance. Commercial SHS and PTFE-based surfaces were chosen as representative icephobic materials and they were applied on test plates. Enamel coating was used as a reference material. Icephobic plates were immersed in two different commercial deicing fluids to simulate a situation where liquids remained on the airframe surfaces for different amounts of time before take-off. The authors observed that the two liquids had different impacts on the surface's wettability. Type-I deicing fluid showed low or no effect on the performance of SH and PTFE coating, on the other hand, Type-IV deicing fluid was capable of strongly contaminating surfaces by drastically reducing their icephobicity and consequently increasing their ice adhesion strength.