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 ?"

Comments

Wonderment

[SanLouBlues]

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.

Re:Wonderment

[racermd]

The F117A is called the Nighthawk. However, most pilots call it the "Wobblin' Gobblin" because it's aerodynamically unstable requiring computer-controlled corrections at a very high frequency while in-flight. Early tests didn't have the computer code particularly tweaked so the aircraft tended to shimmy around (wobble) quite a bit.

The shape of the aircraft is designed to reflect the majority of radio waves directly away from the source and the coating is designed to absorb the remaining radio frequencies, not light. But it does appear to be based on the same priciple as this super-black material. From what I understand of RAM (Radar Absorbing Material), there are small pockets on the surface that are designed to trap and scatter the radio waves until they've almost completely dissipated. The color of the material is rather arbitrary, as I've seen it painted in "desert-camo" in photos taken before it was made public (to hide it better against the sandy-colored ground in the desert where it was being tested). Just before being made public, it was painted black to hide better at night in the sky, which is it's intended primary operating time/environment. Making it even *more* black wouldn't make it much more "stealthy". If you're looking for IR signatures, the engine exhaust would probably be more of a giveaway even though it's cooled to about 800F or so. And because it's in the sky, a UV scan would probably be useless as space (the sky's background) is filled with UV. Blocking even more UV makes it a black mark on a light background.

I might have a use for this super-black material to coat the insides of my projection TV, as well as cover the windows during movie nights! Perhaps even using this on road signs in addition to the super-relective paint the DOT already uses can make road signs easier to see at night due to increased contrast and less glare. Oh, and telescopes, too. Kinda neat, overall.

black

[qoncept]

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.

Re:The name

[sh00z]

Why don't they name materials better today?

Gene Wolfe coined a better word circa 1980. It's fuligin . (Just search on 'blacker than black')

Materials Science

[JumpingBull]

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?

Solar Power.

[miffo.swe]

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.

To get it darker...

[MickLinux]

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.