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.
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
Well... in physics, the sun is often used as an example of a "black body", so one may even say it's black enough as it is ;-)
"First lesson," Jon said. "Stick them with the pointy end."
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?
Here is another example.
/syle
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
HCl acting on Zinc plate can produce a very black surface. In about 1980 I experienced the chemical effect and read about it. The article I read had a microscopic view of its surface and it indeed had striking peaks and valleys.
The intent was to use it in cameras in to enhance the already black shrouds fore of the camera lenses in space.
It was very odd looking at something so black.
No, diffraction spikes are just what they are named: diffraction spikes. Diffraction is not reflection, and an ultra-black surface can still diffract.
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
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.
Linux, because my mother says so!
Actually this "black paint" would probably help for those LIDAR guns the cops are using. Painting front and rear ends of your car along with a good laser detector should help reduce your chances of getting caught spe... um... going just a little bit to fast.
In fact I remember reading an article in "Car and Driver" several years ago that did some testing with LIDAR guns and driving with you headlights on. IIRC driving with your high beams on would reduce the effectiveness of the LIDAR gun by a couple hundred feet. C-n-D even suggested installing high power off road lights with IR filters on them to even further reduce the effective range (giving you some time to slow down before the LIDAR is able to get a reading.)
Of course it seems those damn reflective license plates screw the whole thing up.
Life moves pretty fast; if you don't stop and look around once in a while, you could miss it. -FB