Two scientists from the University of Rochester have come up with a method of using powerful laser beams to make metals extremely water repellent sans the need for temporary coatings.

Making metals extremely difficult to wet, or super-hydrophobic, offers many potential applications, such as preventing rust, anti-icing and maintaining sanitation, but hydrophobic materials currently depend on chemical coatings, which means that the ability of the material to repel water could wane over time as the coating is rubbed off.

Chunlei Guo and Anatoliy Vorobyev from The Institute of Optics at the University of Rochester in New York, however, were able to use a laser-patterning technique. The researchers were able to do this by subjecting surfaces of metals to bursts of laser, to give them new hydrophobic properties.

"We create a multifunctional metal surface by producing a hierarchical nano/microstructure with femtosecond laser pulses," the researchers wrote. "The multifunctional surface exhibits combined effects of dramatically enhanced broadband absorption, superhydrophobicity, and self-cleaning."

The method, which is built on an earlier research employing the same technique to turn metals black, creates super-hydrophobic and optically highly absorbent surfaces that can be suitable for a number of practical uses.

"Some potential applications for anti-icing surfaces include protection of aerofoils, power transmission lines, pipes of air conditioners and refrigerators, and radar or telecommunication antennas," Guo and Vorobyev said.

The surfaces of laser-treated metal repel drops of water, causing them to bounce off and giving them no chances to freeze. These drops of water also take the dust on the surface of the metal along with them, which is essentially a form of self-cleaning. The researchers tested the self-cleaning quality of the treated material by dumping dust from a vacuum cleaner on the surface and removing them with just a few drops of waters.

The researchers likewise pointed out that the treated surfaces are more slippery and have a better water repelling capacity compared with Teflon, which is often used in non-stick frying pans. Since they absorb more light, there is also the potential the treated metals can help the solar industry, where better solar absorbers are known to provide better conversion of solar energy into electrical or thermal energy.

The researchers in particular are excited for the potential application of the materials in developing countries. The Bill and Melinda Gates Foundation, which helped support the work, is eyeing the procedure to help deliver improved sanitation in impoverished counties where there are high demands for limited water supply.

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