Spray-on coating that makes removing ice easy, affordableAmy Walsh (Author) Published Date : Mar 13, 2016 19:46 ET
On your car windshield, ice is something that you do not want and it can be extremely dangerous on an airplane, a wind turbine, an oil rig or power line. And chemical melting agents or labor-intensive scrapers and hammers, become difficult and an expensive work.
That could soon change thanks to a durable, inexpensive ice-repellent coating developed by University of Michigan researchers. Thin, clear and slightly rubbery to the touch, the spray-on formula could make ice slide off equipment, airplanes and car windshields with only the force of gravity or a gentle breeze.
The new coating could also lead to big energy savings in freezers, which today rely on complex and energy-hungry defrosting systems to stay frost-free. An ice-repelling coating could do the same job with zero energy consumption, making household and industrial freezers up to 20 percent more efficient. The coating is detailed in a new paper published in the journal Science Advances.
Made of a blend of common synthetic rubbers, the formula marks a departure from earlier approaches that relied on making surfaces either very water-repellent or very slippery.
Researchers had been trying for years to dial down ice adhesion strength with chemistry, making more and more water-repellent surfaces, said Kevin Golovin, a doctoral student in materials science and engineering. We've discovered a new knob to turn, using physics to change the mechanics of how ice breaks free from a surface.
Led by Anish Tuteja, associate professor of materials science and engineering, the team initially experimented with water-repelling surfaces as well, but found that they weren't effective at shedding ice. But during their experiments, they noticed something unexpected: rubbery coatings worked best for repelling ice, even when they weren't water-repellent. Eventually, they discovered that the ability to shed water wasn't important at all. The rubbery coatings repelled ice because of a different phenomenon, called interfacial cavitation.
Nobody had explored the idea that rubberiness can reduce ice adhesion, Tuteja said. Ice is frozen water, so people assumed that ice-repelling surfaces had to also repel water. That was very limiting.
The new coatings stood up to a variety of lab tests including peel tests, salt spray corrosion, high temperatures, mechanical abrasion and hundreds of freeze-thaw cycles.
The team has also found that by slightly altering the smoothness and rubberiness of the coating, they can fine-tune its degree of ice repellency and durability. Softer surfaces tend to be more ice-repellent but less durable, while the opposite is true for harder coatings. Golovin believes that that flexibility will enable them to create coatings for a huge variety of applications.
An airplane coating, for example, would need to be extremely durable, but it could be less ice-repellent because of high winds and vibration that would help push ice off, Golovin said.
I think the first commercial application will be in linings for commercial frozen food packaging, where sticking is often a problem. We'll probably see that within the next year, Tuteja said.
The team received funding and assistance from the U-M MTRAC program, created to support new innovations that demonstrate high commercial potential.
Spray-on coating that makes removing ice easy, affordable