
Laser-generated surface structures create extremely water-repellent metals - Zaheer
http://www.rochester.edu/newscenter/superhydrophobic-metals-85592/
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SixSigma
A great achievement.

I would like to have seen it dipped. Also demonstrated with contaminated water
of some kind, maybe flour & water paste.

He states it would not degrade, but surely expansion and contraction will take
a toll on nanoscale etchings, as well as abrasion and acid content of airborne
contaminants.

~~~
tonylemesmer
The surface, upon visual inspection in the video looks rough. What happens say
if the surface is regularly in contact with skin during a practical
application? Does the skin get abraded into the microstructure of the material
surface and degrade its hydrophobic properties?

Looks amazing though watching the water spread out and spring back that much.
Simply incredible.

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wheaties
And Chunlei does it again. I was an undergraduate when he arrived and helped
set up the first UHV chamber for his initial tests. Let me just say that not
only is he brilliant but he is also about as down to earth a person as you
could ever meet. He seriously has no ego, is easy going and has an internal
drive that's unbelievable.

If he ever wants to start a company, whomever he reaches out to, fund him.

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jcrites
I would love to learn more about the structure of the patterns etched into the
metals. I took a quick look through the links from the article, but didn't
find anything with meat. Does anyone have a link?

I'd love to see it under a microscope, or see a visualization of the pattern.
Is the strategy to maximize the surface area of an existing hydrophobic
material?

~~~
McKayDavis
Link to the paper [1] (with microscopy images) in the Journal of Applied
Physics leads the 3rd paragraph of the article.

[1]
[http://scitation.aip.org/content/aip/journal/jap/117/3/10.10...](http://scitation.aip.org/content/aip/journal/jap/117/3/10.1063/1.4905616)

~~~
darkmighty
Fantastic, thank you

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jacquesm
Shark skin has similar properties. The sharks use it for super efficient
swimming, it reduces their drag considerably.

[http://www.asknature.org/strategy/038caf2e453c09b3016465cc6c...](http://www.asknature.org/strategy/038caf2e453c09b3016465cc6ca93605)

Car wash companies will hate this stuff, and wouldn't it be nice if it could
be etched into windshields, no more wipers!

~~~
imaginenore
You still need to wash off the dust, so some sort of wipers are needed still.

When swimming, the drag is pretty minor, most of your energy is spent on the
displacement of water. That's true with fish, and with ships and boats.

~~~
thret
"As the water bounces off the super-hydrophobic surfaces, it also collects
dust particles and takes them along for the ride... Better yet, it remains
completely dry."

~~~
scott_karana
That requires a sufficient water-to-dust ratio. Driving jeeps in the Congo, or
having dust blown up from dunes in a sudden gust, will require wipers. Not to
mention pollen.

~~~
soperj
Couldn't you still have sprayers that would help with this?

~~~
scott_karana
Hmm, that's not a bad idea! Current sprayers would obviously be inefficient
because they rely on wipers to spread fluid widely over the windshield, but
I'm sure that could be changed. (Such as a top pressure-rail for dispensation)

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jcrites
Do hydrophobic materials interact differently with gases as well? What would
the air flow be like over a wing made out of a superhydrophobic material like
this? Would it facilitate or disrupt airflow, or not matter?

~~~
jacquesm
Yes, that's been done:

[http://www.lufthansa-technik.com/famos](http://www.lufthansa-
technik.com/famos)

See sharkskin bit above.

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mapt
Hydrophobicity alone is only so useful.

Teflon became a thing because it's both hydrophobic and lipophobic. There are
lots of hydrophobic surfaces that work very well until you get dirt, finger
oils, soap, or just about anything that isn't water-soluble on them. There may
also be an issue here with friction damage.

Hopefully the _technique_ here can be adapted to practical products.

~~~
darkmighty
The technique is extremely flexible. I'm sure they'll figure out an etching
pattern that is both extremely lipophobic and hydrophobic. Only hydrophobia
has many applications already.

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jader201
I wanted to know more about the practical applications of the syperhydrophilic
metals (the counter-technology of the one discussed here), and found this
video [1] with Chunlei informative.

[1]
[https://www.youtube.com/watch?v=JtDPsWd6Yqw](https://www.youtube.com/watch?v=JtDPsWd6Yqw)

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acd
I'm looking for superhydrophobic materials for my next car so its easier to
keep clean.

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venomsnake
Am I twisted when I first thought of non stick, non coated cookware when I saw
the title.

Great achievement.

~~~
hkmurakami
Wouldn't a hydrophobic surface attract oils?

(maybe that's only the case for chemical hydrophobicity rather than
structural)

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kendallpark
I think this could have a great impact on water vessels. I wonder if they can
do the same sort of thing on a fiberglass surface...

It's a good thing the Olympics banned those full-body swimsuits. This would be
the next million-dollar suit.

~~~
contingencies
My thoughts exactly... maybe because I'm reading _Sail Performance_ at the
moment! Weight, durability and shapability would be important properties vs.
the nominal reduction in drag, though.

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jtchang
This is awesome! I look forward to my teflon pans that I don't have to throw
away after 6 months because they stop working.

~~~
sjtrny
6 months? I think you're doing something wrong here. Keep teflon coated
material to low temperatures, use plastic/wood/silicone utensils and avoid
abrasive cleaning techniques.

~~~
hueving
>Keep teflon coated material to low temperatures

How exactly do you cook with it then?

~~~
m_eiman
[https://en.wikipedia.org/wiki/Polytetrafluoroethylene#Safety](https://en.wikipedia.org/wiki/Polytetrafluoroethylene#Safety)

"While PTFE is stable and nontoxic at lower temperatures, it begins to
deteriorate after the temperature of cookware reaches about 260 °C (500 °F),
and decomposes above 350 °C (662 °F).

…

Meat is usually fried between 204 and 232 °C (399 and 450 °F), and most oils
start to smoke before a temperature of 260 °C (500 °F) is reached, but there
are at least two cooking oils (refined safflower oil and avocado oil) that
have a higher smoke point than 260 °C (500 °F). Empty cookware can also exceed
this temperature when heated."

~~~
ericd
This is a pretty big design flaw for someone like me who loves putting a good
sear on steak. Good thing cast iron is fairly cheap...

~~~
tobz
Did you have some implicit expectation that you could heat it for an arbitrary
amount of time, at full power, and it would just be fine? Almost all of the
spot checking I just did shows temperature warnings / upper limits of around
450 degrees F for non-stick pans, right on their packaging.

Also, equivalently-sized cast iron pans are almost always cheaper than their
quality non-stick (i.e. Calphalon) counterparts, and you can restore them if
you jack up the seasoning on them.

~~~
maxerickson
Did you reply to the wrong comment?

The comment you reply to doesn't complain about their use of teflon (a
complaint you imply in your first paragraph) and they praise the cheapness of
cast iron (which you repeat with an 'also' in your second paragraph, the
'also' makes it look like you are trying to correct their understanding of the
relative situation).

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canberroid
I wonder what sort of metals this process would work with effectively and
whether surfaces can be reprocessed over time.

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omegant
Honest question, would steel rust just by liquid water, or vapor and oxigen in
the air will make it rust eventually?

~~~
yourapostasy
Water vapor in the form of humidity is sufficient to initiate the rusting
process.

Most questions along this line are addressed on this page:

[https://van.physics.illinois.edu/qa/listing.php?id=485](https://van.physics.illinois.edu/qa/listing.php?id=485)

Note that if you try to avoid the formation of rust by submerging your steel
in water, thinking that will remove the oxidative air component, you run into
corrosion issues unless you are submerging in a tank of constantly refreshed
distilled water.

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Pronounce
I was hoping to see the drop size decreased to the point where it no longer
was repelled.

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yihyeh
This specifically repel water, or can it repel any liquid?

~~~
kendallpark
Generally, hydrophobic substances won't repel nonpolar substances such as oil.

[http://en.wikipedia.org/wiki/Hydrophobic_effect](http://en.wikipedia.org/wiki/Hydrophobic_effect)

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kozlinov
Awesome. Looking forward for a finally lipophobic smartphone. In fact, in the
future all surfaces of consumer electronics and other stuff should be
superhydrophobic.

~~~
wklauss
I think there are far better ways to do this on a small object of limited
lifespan like a smartphone, not to mention that metal is not an ideal way to
make a smartphone. You can use it some surfaces, but at some point you'll need
plastic and glass.

~~~
kozlinov
"I think there are far better ways to do this on a small object of limited
lifespan like a smartphone"

Namely?

~~~
wklauss
Simple hydrophobic coating. It wears out eventually, but by the time it does
your device is already gathering dust in a drawer.

