Researchers believe they’ve found a new way of dealing with the problem of ice buildup.
Their inspiration came from the wings of Gentoo penguins, who swim in the ice-cold waters of the south polar region with pelts that remain ice-free even when the outer surface temperature is well below freezing.
Ice buildup on power lines and electric towers brought the northern US and southern Canada to a standstill during the Great Ice Storm of 1998, leaving many in the cold and dark for days and even weeks. Dealing with ice buildup typically depends on techniques that are time consuming, costly, and/or use a lot of energy, along with various chemicals.
“We initially explored the qualities of the lotus leaf, which is very good at shedding water but proved less effective at shedding ice,” says Anne Kietzig, an associate professor in chemical engineering at McGill University and the director of the Biomimetic Surface Engineering Laboratory.
“It was only when we started investigating the qualities of penguin feathers that we discovered a material found in nature that was able to shed both water and ice.”
“We found that the hierarchical arrangement of the feathers themselves provides water-shedding qualities, while their barbed surfaces lower the adhesion of ice,” explains Michael Wood, a recent PhD graduate who worked with Kietzig, and is a coauthor of the paper in ACS Applied Material Interfaces. “We were able to replicate these combined effects through a laser-machined woven wire mesh.”
“It may seem counterintuitive, but the key to ice shedding is all the pores of the mesh which draw water in under freezing conditions,” says Kietzig. “The water in these pores is the last to freeze, creating cracks when it expands, much like you see in the ice cube trays in your freezer. We need such little force to remove ice from our meshes because the crack in each of these pores easily snakes along the surface of those woven wires.”
The researchers carried out wind-tunnel testing of surfaces covered by the steel mesh and found that the treatment was 95% more effective at resisting ice buildup than an unenveloped sheet of polished stainless steel. Because there are no chemical treatments involved, the new approach provides a potentially maintenance-free solution to ice buildup on wind turbines, electric towers, and power lines, as well as drones.
“Given the number of regulations in place in passenger aviation and the risks involved, it is unlikely that airplane wings will ever be simply wrapped in metal mesh,” adds Kietzig.
“It is, possible, however, that the surface of plane wings may one day incorporate the kind of texture that we are exploring, and that de-icing will occur thanks to a combination of traditional de-icing techniques working in concert in wing surfaces that incorporate surface texture inspired by penguin wings.”
Source: McGill University
