Nano coating can save power lines from freezing rain

Monday, April 12, 2010 @ 10:04 PM gHale


Just think of the problems freezing rain can cause at plants across the world. Preventing that potential chaos when freezing rain collects power lines, roads and even aircraft for that matter would be an important factor in keeping plants up and running safely.

There is now a new technology that is a nanoparticle-based coating developed in the lab of Di Gao, a chemical and petroleum engineering professor in the University of Pittsburgh’s Swanson School of Engineering, that thwarts the buildup of ice on solid surfaces. They can also easily apply the coating to the surface.

The paper, by lead author and Pitt doctoral student Liangliang Cao, presents the

This coating is the first evidence of anti-icing properties for a burgeoning class of water repellants known as superhydrophobic coatings. These thin films mimic the rutted surface of lotus leaves by creating microscopic ridges that reduce the surface area to which water can adhere. But researchers said because ice behaves differently than water, the ability to repulse water does not readily apply to ice inhibition.

Superhydrophobic coatings must undergo specific formulation to ward off ice buildup, the researchers said. Gao and his team created different batches made of a silicone resin-solution combined with nanoparticles of silica ranging in size from 20 nanometers to 20 micrometers, at the largest. They applied each variant to aluminum plates then exposed the plates to supercooled water (-20 degrees Celsius) to simulate freezing rain.

While each compound containing silica bits of 10-or-fewer micrometers deflected water, only those with silica pieces less than 50 nanometers in size completely prevented icing, said Pitt doctoral student Liangliang Cao, who was the lead author of a paper on the subject. The minute surface area of the smaller fragments means they make minimal contact with the water. Instead, the water mostly touches the air pockets between the particles and falls away without freezing. Though not all superhydrophobic coatings follow the Pitt recipe, the researchers conclude that every type will have a different particle-scale for repelling ice than for repelling water.

Gao tested the coating with 50-nanometer particles outdoors in freezing rain to determine its real-world potential. He painted one side of an aluminum plate and left the other side untreated. The treated side had very little ice, while the untreated side was completely covered. He produced similar results on a commercial satellite dish where the glossed half of the dish had no ice and the other half remained encrusted.

A video showing an aluminum plate glazed with Gao’s superhydrophobic coating is at www.pitt.edu/news2009/ice.html.



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