Watch: how to laser etch metal surfaces to make them either love or hate water

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I’ve seen the hydrophobic surface video, but not the hydrophilic surface in action. Cool! I wonder how the etching affects other properties of the material. Would a windshield still meet all other safety requirements?

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I am quite sure that etched metal is not a legal windshield material :wink:

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I wonder how far this can be pushed?

Could a hyprophilic/phobic surface be made directional, so that water ‘flows’ across it, even in the abscence of some other force (such as gravity, or wind)? Could the water be made to ‘flow’ uphill?

Gotta wonder if the effect lasts if the surface gets dirty… if not, then it’ll only be practical in a clean-room type environment.

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With a wick-like structure, yes.

Capillary action could allow the water to flow uphill to a some extent, but there are limits as I understand it. Unless you have something (like evaporation) pulling the liquid out when it gets to the top, it’s not going to go anywhere higher. You can’t just have something wicking up hill infinitely against pressure from above. The energy to keep going needs to come from somewhere.

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Yes. But you can get it fairly high anyway. Then it is an engineering task to figure out (by working on both the “demand” and the “supply” side of the height) how to make it “high enough”. Usually you don’t need infinite heights.

A great example of capillary action used for liquid transfer regardless of orientation is heat pipes.

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The Leidenfrost Effect. One of the things that you could use it for is to draw liquid coolant over processors with their own heat.

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This is pretty neat stuff, but as with most of these breakthroughs, there are a bunch of unexplained details I wish they’d covered:

  • Electron microscope imagery of the surface characteristics (or even CGI microscopic mockup) and how they interact with the surface tension.

  • How durable is this material? Can you hand wash it, or does one good scratch do it in?

  • As @DavidK44 indicated: Do any types of liquids or fine solids that infiltrate the etching and denature it? If so, any way to refresh it?

  • If it is repelling corrosive liquids, does it somehow avoid contact altogether? Or are there minimal points and edges making contact? What about reaction with corrosive gas particles?

  • What does the texture feel like against skin?

  • Will this etching work for other materials? What about flexible materials? (love to have clothing with these properties)

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Thought. These surface nanostructures will be very prone to damage/wear.

What about some sort of composite material, where these structures are within the bulk? If you remove the surface, the exposed material then can preferentially degrade in a way to expose a fresh hydrophobic (or hydrophilic) structure, making itself self-renewing.

I’d be curious to see how the treatments would effect boiling… would water boil or would there be no chance for stream bubbles to nucleate?

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Love, Hate, what is it with all these extremes? Why can’t we just etch the metal so that it only gets mildly annoyed at water?

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That’s called “rust”.

Though, that does not have to be just “mild”. There are cases of people killed by entering confined spaces because the oxygen content in the air was depleted by rusting iron. The same effect can lower pressure in enclosed tanks so badly they get sucked in. And it does not have to be a slow process; a tank with wet magnesium chloride at its bottom dropped its oxygen content down to 1% in a single day.

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I don’t think we need no steenkeeng etched metal.

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