Slashdot Mirror
Blacker Than Black
An anonymous reader writes "British scientists at the National Physical Laboratory in London have invented the darkest material on Earth. 'It could revolutionise optical instruments because it reflects 10 to 20 times less light than the black paint currently used to reduce unwanted reflections. The key to the nickel and phosphorous coating's blackness is that its surface is pitted with microscopic craters.' Wonder how effective it would be as a solar heating surface ?"
Wonder how effective it would be as a solar heating surface ?
That probably depends on the specific heat of the material.
I myself wonder how physically resilient this material is, what it's impedance is, and whether it isn't extremely similar the blackbird surface material.
I would say that the solar surface is hot enough as it is!
Enig? Det alt for hot det smor!
Goths just got scarier. "Black as night, faster than a shadow" -Judas Priest- "Hell Bent For Leather"
"Suburbia is where the developer bulldozes out the trees, then names the streets after them."
If it reflected one times less that'd mean it was reflecting nothing at all, so what happens when it reflects 10 times less?
My high school physics teacher had a piece of "black," though not as black as this. He said he'd put it against walls and students sitting at the other end of the room would think there was a hole, he said. By the time I saw it, it was old and had gotten too dusty to be very impressive.
Whale
Why don't they name materials better today? What is interesting in the name "Super-black"? Nothing!
I suggest we call it Darkonium or something...
None.
None more black.
NIGEL: I think he's right, there is something about this, that's that's so black, it's like; "How much more black could this be?" and the answer is: "None, none... more black."
-Mark
Nigel Fox, who heads the optics group at NPL, said: "When you look at the black, it is an incredibly beautiful surface. It's like black velvet."
Who'll be the first schmuck to paint Jesus or Elvis onto this surface?
Welcome to the Panopticon. Used to be a prison, now it's your home.
The light that is neither transmitted nor reflected is absorbed. If it is totally opaque too it has to be also a good solar heating surface. That said, one might be a very good absorber at particular wavelengths, but transparent or reflective at others. The cavities should act as a blackbody and operate at a wide range of frequencies though.
Gentlemen, you can't fight in here, this is the War Room!
so I know this material has been here on earth since the "Dawn of Man."
I would love to see this used to coat the vanes that support the secondary mirrors of reflector type telescopes. Diffraction spikes (the little spikes on relatively bright stars) are really the reflection of light on these little supports. If you are into photographing nebulae, having a bright star in view can be a real photo killer.
The book 'The Hubble Wars' mentions a coating called 'Martin Black' developed by Lockheed-Martin for use in spy satellites - I wonder how this stuff compares. I found some info Here : The 'Martin Black' is not a paint at all, but a specially etched aluminum surface that acts like an anechoic chamber on a microscopic scale. The surface looks like an array of very steep pyramids a few wavelengths of light apart. It's extremely fragile & expensive to produce, but was never a classified process. Mostly used in aerospace optical hardware such as star trackers & imaging systems that have to work in direct sunlight. Ball Aerospace has a version of this process. It's considered to be a 'proprietary' process, ie they won't tell you how it's done for commercial reasons.
There's a little more detail and a few pictures at http://www.npl.co.uk/optical_radiation/superblack. html
no llamas were harmed in the making of this sig
Scientists estimate this will be the blackest material ever manufactured, until they perfect the technique of mass-producing Hillary Rosen's soul.
Don't Touch It! It's Evil!
Well, now all those people wearing t-shirts saying "I'm only wearing black until they invent something darker" will be very happy! Any idea as to when we'll be able to get it in t-shirt form?
...this is a Good Thing for production instruments, but it won't matter much for research/labwork/prototypes; right now I'm working on laser detection of single atmospheric particles; we needed a *black* coating for the inside of the chamber, but it didn't need to be particularly robust, just dark - so we smoked it with a flame. Carbon black is the least reflective substance known, IIRC it absorbs something like 99.996% of incident radiation...anybody who's seen the inside of an old kerosene lamp chimney knows exactly what they mean in the article when they talk about the 'black velvet' appearance. We did have some problems with it 'popcorning' as we pumped the chamber down, but a staged evacuation with good degassing periods took care of that.
Oh, this would make a great solar heating material - somebody mentioned the specific heat of the material, but as long as you have a thin layer backed by a heatsink, the specific heat doesn't matter (it's just the amount of heat a material can contain per gram; if you have just just a tiny bit of black substance, it doesn't matter how much heat it stores); it's all about the absorbtion.
Facts do not cease to exist because they are ignored. - Aldous Huxley
Pictures are mirrored here: dev/null
A pizza of radius z and thickness a has a volume of pi z z a
This will prove to be useful, for two reasons:
First, it is a better absorber then what we have now, which, as someone pointed out, would make an incremental improvement for things such as solar collectors.
Second, it may find some powerful uses as a black body emitter, which would have some applications for cooling. Specifically, there is a window in the atmosphere where energy can leave the atmosphere ( around one of the IR ammonia lines, IIRC) this may alleviate the greenhouse effect ... maybe ...
As one of my Professors used to say "Progress is measured by progress in Materials Science". He might have been biased, however...
I would be very interested to find out the wavelengths where this is effective.
There are three types of reflectance that I am aware of: mirrors; diffuse reflectors (lambertian surfaces) and a special case of reflectance as found on a dusty surface, such as the moon( which is an aggragation of spherical lambertian surfaces, with special properties). Anyone else know of any others?
This is progress?
offtopic, yes, but somewhat more in the vein of discussion, how does it do on reflecting, say, radar?
- Entertaining Bits from the Ancient Kernel Tree
Humm....
It's obvious that it's highly non-reflective in the visible portion of the spectrum, the question is how "black" is it in other spectrum regimes. Is it equally black in the IR, and/or UV?
Also, remember that a good absorber is a good emitter.
"Oh drat these computers, they're so naughty and so complex, I could pinch them." --Marvin the Martian
The problem with solar power today isnt about efficiency since modern panels have about 70-80% efficiency in heating water. The incoming power is about 1000W per m2. A better absorber wouldnt make the panel that much more efficient.Chromium Oxide have an efficiency of about 92%. Much of the problems lie in how you transport the heat from the panel to the energy storage.Insulation of the panel is something that you have to take into consideration. Cost is also of utter importance since you often have a roof capable of housing more than 30 m2 of panels which in most houses is overkill. To generate water you typically would need about 5 m2 from mars to november.
If this material can make the total cost smaller then its good but if it makes it more expensive it isnt of any use. Robustness and price is what we should look into and not efficiency. A cheap solar panel that lasts for as long as it have to be functional to return the investment is possible today.
The main problem with solar power is that when you need the power most (night/winter) there arent much sun around. Solar Power can never be anything but a valuable complement to something else. All trials of storin the energy longer times have failed miserably so far.
Im not just rambling here, i was a partner in a company manufacturing solar panels some years ago.
HTTP/1.1 400
Blacker than the mood of a web master who just found out that his page was posted on slashdot.
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
Super-black
Technoli
Martin Marietta (now Lockheed Martin) has produced a proprietary "super black" coating for years now. I've seen it, and it is _very_ non-reflective. The coating mentioned in the article sounds similar.
"Martin Black" is proprietary though, so if you want a part coated you have to send it to Lockheed.
To get it even darker, plate a bunch of razor blades with this material, and then stack them.
My father used stacks of razor blades as a heat dump for lasers in his fusion research at University of Wisconsin.
He showed with pencil and paper how the razor blades successively reflect the light into the gaps between the blades, without turning it around. Thus, they absorb all the light, and make a great blackbody.
Just as an interesting note: This was back in the early 70's, at a time when cost-efficient fusion was only a decade away, and had been only a decade away for 20 years. As part of his defense, he was asked whether it would be practical any time soon. His answer was no. When asked why, he pointed out that the reaction that was giving them some success was the D-T reaction, and that Tritium was so rare that it would never be a practical fuel.
That essentially did not earn the pleasure of others in the field, and kept him out of that field -- perhaps a blessing, since success might have doomed his life to failure.
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
... how long before /. reports that someone has a case mod made of this?
Tuus crepidae innexilis sunt.
"player 4 hit player 1 with 0 stroms"