Super black
Super black is a surface treatment developed at the National Physical Laboratory in the United Kingdom. It reflects much less light than the darkest conventional matte black paints available previously.
Conventional black paint absorbs about 97.5% of the incident light. Super black absorbs approximately 99.6% of light at normal incidence. At other angles of incidence, super black is even more effective. At an angle of 45°, super black absorbs 99.9% of light.
The technique used for super black is based upon chemically etching a nickel–phosphorus alloy.[1][2]
Applications for super black are in specialist optical instruments to reduce unwanted reflections. The disadvantage of this material is its low optical thickness, as it is a surface treatment. As a result, infrared light of a wavelength longer than a few micrometers penetrates through the dark layer and has much higher reflectivity. The reported spectral dependence increases from about 1% at 3 µm to 50% at 20 µm.[3]
In 2009, a competitor to the super black material was developed based on carbon nanotubes called Vantablack, that has a relatively flat reflectance in a wide spectral range.[4]
In 2011, NASA and the US Army began funding research in the use of nanotube based super black coatings in sensitive optics.[5] Nanotube based superblack arrays and coatings have recently become commercially available.[6]
See also
- Emissivity
- Black hole, a gravitationally bound absorber for all incident matter and radiation
- Black body, an ideal, a perfect absorber for all incident radiation
- Vantablack, absorbing up to 99.965% of radiation in the visible spectrum
References
- ^ "Mini craters key to 'blackest ever black'". Newscientist.com. 6 February 2003. Retrieved 2015-07-14.
- ^ "Highly Absorbing Surfaces for Radiometry". January 2003. Archived from the original on 2005-06-27.
- ^ Brown, Richard J. C.; Brewer, Paul J.; Milton, Martin J. T. (2002). "The physical and chemical properties of electroless nickel???phosphorus alloys and low reflectance nickel???phosphorus black surfaces". Journal of Materials Chemistry. 12: 2749. doi:10.1039/b204483h.
- ^ "NASA - NASA Develops Super-Black Material That Absorbs Light Across Multiple Wavelength Bands". Nasa.gov. 2011-11-08. Retrieved 2015-07-14.
- ^ [1] Archived March 2, 2014, at the Wayback Machine
- ^ "Aligned Carbon Nanotube Arrays and Forests on Substrates". Nano-lab.com. Retrieved 2015-07-14.
External links
- Beckhusen, Robert (Dec 24, 2012). "Army Goes Goth with "Super-Black" Materials". Wired.
- Quick, Darren (Nov 9, 2011). "NASA's new super-black nanotube-based material is good news for star-gazers". New Atlas.
Trade journals:
- "Super Black Coatings on a Mission". Paint Square. Aug 19, 2014.
Part of NASA's Materials Coating Experiment
- "Magic Black, Vacuum Black". Advanced coatings. Acktar.
Inorganic, thin coating, deposited using vacuum deposition technology
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