Thursday, 24 July 2014
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Hydrophobic coating prevents the build-up of ice on aircraft

A team of Japanese scientists has developed a water-repellent surface that can prevent ice from forming during flight.

Unlike current in-flight anti-icing techniques, the researchers envision applying this new anti-icing method to an entire aircraft like a coat of paint.

As aircraft fly through clouds of super-cooled water droplets, areas around the nose, the leading edges of the wings and the engine cones experience low airflow, said Hirotaka Sakaue, a researcher in the fluid dynamics group at the Japan Aerospace Exploration Agency (JAXA).

This enables water droplets to form on aircraft to create an icy layer. If ice builds up on the wings, it can change the way air flows over them, hindering control and potentially making the aircraft stall.

Current anti-icing techniques include diverting hot air from the engines to the wings, preventing ice from forming in the first place, and using inflatable membranes known as pneumatic boots, which crack ice off the leading edge of an aircraft’s wings.

The super-hydrophobic coating being developed by Sakaue, Katsuaki Morita, a graduate student at Tokyo University, and colleagues from the Kanagawa Institute of Technology and Chuo University works by preventing the water from sticking to the aircraft’s surface in the first place.

According to a statement, the researchers developed a coating containing microscopic particles of polytetrafluoroethylene (PTFE), which reduces the energy needed to detach a drop of water from a surface.

The PTFE microscale particles created a rough surface — and the rougher it is, on a microscopic scale, the less energy it takes to detach water from that surface.

The researchers varied the size of the PTFE particles in their coatings, from 5–30 micrometers, in order to find the most water-repellant size.

By measuring the contact angle — the angle between the coating and the drop of water — they could determine how well a surface repelled water.

The team will present its findings in a poster session at the American Physical Society’s Division of Fluid Dynamics meeting taking place this week at the San Diego Convention Center in California.


Readers' comments (2)

  • Does anyone have any more details of this product and/or of the tests that have been carried out?

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  • This sounds very similar to a number of products that are already available for aircraft. The article indicates that they are using PTFE as part of the product. PTFE, commonly known as Teflon has been available for aircraft for a while. The biggest issue with applying Teflon properly to an aircraft surface is that it needs to be cured (baked at relatively high temps - expensive process) to the paint in order to achieve the full benefit. Another product, Xzilon, has been available for a number of years now and cures at ambient temperatures. From my experience, it does the same thing as being reported above as far as repelling water droplets, etc (I'm not aware of any specific ice tests - very difficult and expensive to perform). Xzilon & Teflon (properly applied) also reportedly have the benefit of extending paint life, thereby lowering costs. I'd also be curious too how having a "rough surface" affects airflow and drag related issues.

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