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.