Metal Ready To Take Its Revenge From Water

hydrophobic
Now, it’s time for the metal to take revenge from water that often damages metals, causing rust, wear and decay.

University of Rochester scientists Chunlei Guo and Anatoliy Vorobyev have developed a technique using extremely precise laser patterns that renders metals superhydrophobic: in simple, it can be described as water-repellent.

Just imagine a much more powerful Teflon — except that Guo and Vorobyev’s material isn’t a coating but part of the metal itself. Water actually bounces off the surface and rolls away.

The advantages of the new experiment are many and more effective in case of air planes. No more worrying about de-icing, because water won’t be able to freeze on aircraft in the first place.

Secondly, sanitation in poor countries, an idea close to the heart of the Bill and Melinda Gates Foundation, which helped fund the project. Thanks to the surface’s repellent properties, it’s essentially self-cleaning.

Incidentally, Guo was inspired by a project in which he and a team treated a variety of materials to make them superhydrophilic — that is, water-attracting.
Describing about the invention, he said, he had worked with a variety of materials — not just metal but semiconductors, glass, other things. Even on a vertical surface, he said, the effect was very strong. If a drop of water was dropped on the bottom of the surface, it would actually shoot up against gravity, uphill. The process really motivated them to look into this reverse process.

In the next step, the two compared the surface to that of a lotus leaf, which has a hierarchical structure containing a larger micro-scale structure and is superhydrophobic.
And like the lotus leaf, because the laser-patterned metal is so water-repellent, it has self-cleaning properties. During the experiment, Guo dumped some household dust from a vacuum cleaner on a treated surface. Just a few drops of water collected the dust, and the metal remained dry.

The scientists used platinum, titanium and brass as sample metals, but Guo says he believes it could work for a wide variety of metals — not to mention other substances.
The process is still very much of the lab. It took the scientists an hour to treat a 1-inch-by-1-inch sample and required extremely short bursts of the laser lasting a femtosecond, or a millionth of a billionth of a second.

Guo is optimistic about ramping up the process for industrial use, and he says the goal for the sanitation project is to “really push the technology out” in the next two or three years.

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