# Superhydrophobic Coating Solutions for Deicing Control in Aircraft
## 3 Superhydrophobic Surface with Icephobic Behaviour for Aircraft Applications
### SHS Tested in Flight Conditions
Furthermore, less stable wettability of spin coated sample with respect to spray coated one was observed, and icebrobleity decreased after each icing/deicing cycle. Continuing the search for a performance coating with icephobic behaviors for aerostructure components, [PERSON] et al. [37] proposed the use of quasicrystals (QCs) metallic materials. They are applied by means of high-velocity oxyfuel thermal spray Al-based QCs on common aeronautic materials. In particular, the work aimed to compare the QCs coating with PTFE, PU-based commercial paints and bare metal considering also the surface roughness. To do that, two QC materials were chosen and tested both in an \"as deposited\" state and after grinding with SiC paper to allow surface roughness similar to the reference. As deposited QCs materials showed different CA, for QC1 it was 158\({}^{\circ}\) with a CAH of 58\({}^{\circ}\), for QC2 CA = 114\({}^{\circ}\) and CAH = 60\({}^{\circ}\). All other reference materials showed contact angles less than 101\({}^{\circ}\) (PTFE). Ground QCs lost their wettability in fact CA for QC1 decreases to 57\({}^{\circ}\) and QC2 to 72\({}^{\circ}\). IWT tests were performed both in glaze and rime ice conditions and ice accretion was evaluated. Under rime and glaze conditions the mass of ice accreted on all QCs coating was less than ice on standard metals. A different behavior was observed for the ice adhesion test, in this case, roughness played a critical role, the best results (low shear stress) were observed for the low roughness sample (PTFE and PU reference), and  
Figure 7: Ice adhesion strength of the anodized samples in rime ice, mixed/rime ice, mixed/glaze and glaze ice conditions with respect to the reference bare AA2024 surface. Reprinted from Surface & Coatings Technology journal, 405, [PERSON], [PERSON], [PERSON], [PERSON], Development of nanostructured icephobic aluminum oxide surfaces for aeronautic applications, 126652, Copyright (2021), with permission from Elsevier [36]. lower values than as-deposited QCs were observed for ground QCs samples even lower than the value obtained for the aeronautic paint. The results thus lead to the statement that for ice adhesion, roughness played a role more important than wettability which seemed to be important in the mass of accreted ice, and finally that QCs materials are promising in terms of durability. Comparing these works, it can be affirmed that roughness is a key factor in the ice adhesion to the surface. Each work concludes by noting that samples with higher roughness, even if SH, show higher shear stress than the unmodified surfaces used as reference. It should be noted, however, that in all these cases the produced SHS shows a macroroughness on the order of microns, while in the only case where an SHS shows performant results, the roughness is below the micron (500 nm, CA = 156\({}^{\circ}\)). In conclusion, we can affirm that superhydrophobicity plays a key role only if it is accompanied by nano roughness that does not allow strong ice interlocking.