We’ve all heard the saying “fight fire with fire.” Well, scientists at Virginia Tech have a new twist on that idea. They’ve come up with a way to “fight ice with ice.”
It could revolutionize the way we de-ice everything from airplanes to windshields without harming the environment.
This time of year, the frost on your windshield warns you it could be dangerous out on the roadways. And the only remedy is sand, salt or slipping and sliding. So out come the salt spreaders, pouring 20 million tons of saline onto U.S. highways alone every year. But salt can only absorb so much water before it washes away into rivers and streams.
“So, what we’re trying to do, is create what we’re calling ‘everlasting salt crystals’ that never get watered down as they harvest all the frost. A new approach, developed by engineers at Virginia Tech, is built on a principle meteorologists have long known about: clouds form when ice crystals attract moisture from the air, due to a change in pressure," says Virginia Tech professor Jonathan Boreyko.
Boreyko and his team of Biomedical Engineering and Mechanics students took a page from that process. They created their own pressure change by making microscoping cuts on a surface like aluminum. That tiny differential creates the pressure change that attracts ice to the tiny, raised areas, leaving the large rest of the surface ice free.
“So, all we’re doing is using some basic patterning on surfaces to micro-pattern or 'etch' little ice stripes across the surface that can then attract all the little moisture from the air leaving the intermediate surface areas between the ice stripes completely dry,” Boreyko says.
That’s because with even just that tiny pressure difference from that microscopic scoring of the surface, when temperatures are cold enough, ice just grows more ice. That ice covers just 10% of the surface. They call it 'sacrificial ice' because it allows the other 90% to stay dry.
Farzhad Ahmadi is grad student working on the project. He says this discovery is game changing, “Because you feel like you have created something that nobody has thought about ”doing in this way.
He’s testing how best to etch those microscopic patterns onto metallic, frost prone surfaces like air plane wings and outdoor heat pumps. But doing that for your car’s windshield may take a little longer. The next step is to figure out how to etch those ten-micrometer wide micro-marks onto a transparent surface.
"Our hope is, that in a matter of just a few years we can have this more less worked out for airplane wings or for outdoor components of the heat pumps. Those boxes you see outside your house that tend to frost over," Ahmadi says. "Car wind shields are trickier because you have to do it on a transparent surface.”
The new take on de-icing doesn’t need energy to function, leaving no carbon footprint.
Note: Radio IQ is a service of Virginia Tech.