Magnetic material lets ice slide right off

Hadi Ghasemi illustrates how a drop of water rolls off his icephobic surface(Credit: University of Houston)

For most people, icy conditions mean a slippery pavement or trying to chip the car out of a freezing glaze, but icing can also bring down aircraft, snap power lines, and cause a surprising amount of structural damage. Now scientists at the University of Houston (UH) have come up with a surprising solution – and it involves magnets.

The problem with icing is that when droplets of freezing or supercooled water strike a surface, they wet or adhere to it, so more and more droplets can join the party. To de-ice a surface, you need to either melt the ice, break it off, dissolve it, or alter the surface so the ice can't stick to it in the first place.

According to Hadi Ghasemi from the UH Department of Mechanical Engineering, "icephobic" surfaces that are non-wetting or liquid infused have shown promise in the past, but suffer from high freezing temperatures, high ice adhesion strength, and high cost.

To get around these problems, his team produced what is called a MAGnetic Slippery Surface (MAGSS), which is a material with a magnetic coating on one side, and a thin layer of magnetic fluid made of suspended iron oxide nanoparticles on the other, outward facing side. When a droplet of water hits the fluid, the magnetic fluid forms a barrier that the droplet can't adhere to so it skitters off before reaching the solid surface beneath.

According to the team, MAGSS is superior to conventional techniques because it can operate at temperatures as low as -29° F (-34° C) compared to -13° F (-25° C) for current materials. Ghasemi plans to develop a way of applying the surface by spraying, with the team seeing applications for this ice-repelling surface in aircraft and the power industry.

The research was published in Nature Communications.

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