Back in 2010, MIT and GE announced the results of research that appeared to have tantalizing implications for greatly reducing the buildup of airframe ice. So called “super-hydrophobic” coatings were shown to cause water droplets to bead up rather than spread out, reducing ice buildup by as much as 70 percent. But after the first exciting release of data, the team went quiet.
It turns out there was a major flaw in the theory: frost. The super hydrophobic coatings (which are said to be easily incorporated into aircraft paint) showed little defense against the formation of frost, which occurs when water freezes directly from a vapor state, or from very small droplets. Once a layer of frost is established, the hydrophobic qualities of the surface — super or otherwise — are rendered useless. MIT’s research showed that the buildup of frost can actually accelerate more dangerous icing from large droplets.
But even back in 2010 the researchers suggested that using a textured surface underneath the super hydrophobic coating could mitigate the negative effects. On Wednesday, members of the same research team announced a report outlining how nano-scale texture would be optimized to minimize the recoil of the droplets. The trade-off would be possible negative effects of the texture on airflow, but the researchers believe they can establish viable compromises in the texture that would minimize airflow distortion while maximizing anti-icing qualities. It’s even possible that certain surface textures could enhance airflow — think, the dimples on a golf ball, or certain jet engine fan blades that use surface textures to improve aerodynamic efficiency.
More research needs to be done, but researchers are optimistic that coatings that passively resist ice buildup could be economically feasible — with implications for applications well beyond just airplanes.
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