Laser Turns All Metals Black

Roland Piquepaille writes "Researchers at the University of Rochester have found a way to change the properties of almost any metal by using a femtosecond laser pulse. This ultra-intense laser blast creates true 'black metal' from copper, gold or zinc by forming nanostructures at the surface of the metal. As these nanostructures capture radiation, the metals turn black. And as the process needs surprisingly low power, it could soon be used for a variety of applications, such as stealth planes, black jewels or car paintings. But read more for additional references and a picture of this femtosecond laser system."

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Laser etching craze

[LiquidCoooled]

How long until you can get your logos engraved onto your laptop/ipod in black (instead of the current efforts).

Hey look the Roland Template Script is back

[Anonymous Coward]

and his additional references [google.com]

Re:Blackness

[ross.w]

It is, but it also insulates a bit. If you paint something black, it emits and absorbs radiant heat with the properties of the paint, not the metal. This is about making the metal itself black so it absorbs/emits more efficiently.

Re:Blackness

[Anonymous Coward]

Guo's research team has tested the absorption capabilities for the black metal and confirmed that it can absorb virtually all the light that fall on it, making it pitch black.

Having an aircraft made out of treated metal would make it one heck of a (visually) stealth plane. As it is, the U.S. stealth planes require a going-over with a fine tooth comb after each mission to ensure no scratches, dents, or chips are in the paint. Presumably a metal approach would reduce turn around time.

Oh yea, and black kicks ass.

Solar collectors

[edwardpickman]

Seems like the perfect coating for solar panels for hot water. The search has always been for the best heat absorbing surface. This type of coating should be the most efficent coating for heat absorbsion.

Re:Applications: Vandalism

[1u3hr]

The article mentions needing no more power than is available from an electrical socket.... Assuming you could then also battery power it, you'd have the potential to vandalize any bare metal in public with black marks that are "impossible" to rub off...

Who says it's impossible to rub off? It's a very thin surface treatment. A quick rub with sandpaper should remove it to ordinary metal. And no reason you coudn't paint over it. Actually paint might adhere better to a fuzzy surface like this, when repainting over over an enamel paint job you take the shine off it with some fine sandpaper first.

Re:Blackness

[bladesjester]

Since other people have pointed out the fact that this wouldn't burn off or rub off easily, one of the other things that this would have as an advantage over paints and powder coats is that they add thickness to the material in question and this (theoretically, at any rate) would not. That would be a big plus for precision insturments. Especially if it has any oxidation inhibiting properties.

Re:Paint lacks an important property

[Petronius.Scribe]

Paint is also heavy - a couple of hundred kilograms for an airliner, and almost a tonne for a B52.

So maybe....

[boojumbadger]

All the unaccounted for dark matter is covered in nanotubes.

May not be such a great idea for consumer items

[Overzeetop]

I would presume that this is a very thin portion of the surface, since there is no data given, and that it sounds like it heats the metal to a vapor (maybe plasma?) and allows it to cool so quickly that it "freezes" in microstructures (excuse me - nanostructures). For all soft metals, then, a simple scratch would reveal the shiny surface free of the effects below the new "coating". Also, a surface with near zero emissivity and high conductivity would likely cause burns very quickly if left in the sun on a summer day. How would you like a nice burn from your car should you accidentally graze your spiffy black racing stripe? Also, wouldn't there be a propensity for these nano-strucutures to foul due to a microseive-like effect - collecting all the crud that just floated by? Seems like a nightmare to clean after pollen season.

It certainly does have some applications, and optics seems to be the obvious place. Having an emissivity of (well, they didn't say) 1e-8 would certainly make baffles more efficient.

Can it be used for long term archival

[Stavr0]

If the laser can be modulated it could be used to etch a quasi-indestructible CD-ROM kind of media. For example gold or titanium could last a long while.

Re:Blackness

[NormalVisual]

For many, many years we've been able to use lasers to spot-anneal metals, which produces a very dark (though not totally black) mark on the metal while introducing no change at all dimensionally. One area where this process gets used quite a lot is in artificial limbs/implants where the foreign body to be introduced needs to be permanently marked for identification but can have absolutely no sharp edges or anything else that might irritate or damage the tissue. This new process sounds like something similar, although the femtosecond laser angle is kind of new. I'm curious to see how practical it turns out to be, as the few femtosecond lasers I've worked with were *extremely* sensitive to temperature changes.

For those having difficulty reconciling the "entire power output of the US from a standard AC outlet" thing, understand that you are radiating for a ridiculously short period of time, so you can get a very high peak power in that pulse while still having a very low average power usage if you can unload a decent percentage of the entire duty cycle's worth of power in that one pulse. The Nd:YAG machines that I worked with were only 90 watts or so CW (continuous wave), but when you cranked the Q-switch down to a low enough rate, you could get a peak power in excess of a quarter-million watts in each 10 microsecond pulse. 10 microseconds is 10 *billion* times longer than a femtosecond (same comparison: one second to 317 years), so you have the possibility of having staggeringly large peak powers in these really short pulses.

Re:anything special?

[MagusSlurpy]

Yes. The nanostructures formed by the laser give the metals much more surface area, thereby enabling a catalytic effect. Expect to see this played with much more in inorganic and organometallic labs very soon.