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Ice formation on propeller blades or aircraft wings can cause major problems. It can limit flight time, increase costs and pose safety and environmental risks.

That is why researchers at SINTEF have developed a new coating material that makes ice removal both more efficient and cheaper—without harming the environment.

Today, ice is usually removed using electrical heating, either with permanent heating systems in the rotor blades, or by temporarily applying chemical de-icing agents. The challenge is that these methods do not provide sufficient protection against the formation of new ice. As a result, they have to be repeated several times, leading to high maintenance costs.

The industry is therefore eyeing the new anti-icing method that SINTEF is developing, according to researcher Christian Karl, who is part of the research team on the project called IceMan. "This is a more effective and long-lasting method for removing ice on technical surfaces. We're seeing that more and more industrial sectors, like wind energy, aerospace, automotive and marine technology, have turned their attention to our solution."

The coating is based on polyurethane, a type of polymer material, and can be sprayed or brushed directly onto the surfaces, giving them ice-repellent properties and slowing down ice formation. The study is in the Journal of Nanoparticle Research.

"In practice, this will mean that supercooled water droplets that land on the rotor blades won't be able to freeze onto the surface. The water will bead up and roll off the surface before it has time to freeze. If, contrary to expectations, it remains there, it will adhere less well and be easier to remove," says the SINTEF researcher.

Fluorine-free solution protects the environment

Research colleague Monika Pilz led the project. She says that the additives are environmentally friendly and are made in such a way that they can easily be scaled up and used in industry settings.

"The goal was to achieve the best possible water repellency and anti-icing ability, while saving both energy and the environment. That is why we looked closely at the complex interaction between the materials and desired properties," says Pilz.

"No fluorine compounds are used in the material compositions, which makes them environmentally friendly. At the same time, the water-repellent additives can be blended with water-based polyurethane paint, which provides an improved ice-repellent coating after drying."

The research results showed that the coating makes it easier for water droplets that hit the surface to roll off, ice builds up to a lesser extent, and freezing is delayed by more than 4 hours at -5°C.

Relevant for wind turbines too

The project has primarily focused on drones and other remotely piloted, unmanned aerial vehicles (UAVs), but the results can also be transferred to use on wind turbine blades.

"Ice formation on wind turbine blades can cause ice to be thrown or to fall off the rotor blades and could damage the surroundings or injure people. The study is important for the wind energy sector, but also for several other applications and sectors," says Karl.

"The way the new coating is made also allows it to be used for other purposes, such as electrical and telecommunications infrastructures and other composite and metal structures in the aviation sector."