super black
{{Short description|Highly light-absorbent surface treatment}}
Super black is a surface treatment developed at the National Physical Laboratory (NPL) in the United Kingdom. It absorbs approximately 99.6% of visible light at normal incidence, while conventional black paint absorbs about 97.5%. At other angles of incidence, super black is even more effective: at an angle of 45°, it absorbs 99.9% of light.
Technology
The technology to create super black involves chemically etching a nickel-phosphorus alloy.{{cite web
|url= https://www.newscientist.com/article/dn3356-mini-craters-key-to-blackest-ever-black.html|title=Mini craters key to 'blackest ever black'
|date=6 February 2003
|publisher=Newscientist.com
|access-date=2015-07-14
|url=http://www.npl.co.uk/optical_radiation/superblack.html
|title=Highly Absorbing Surfaces for Radiometry
|date=January 2003
|archive-url=https://web.archive.org/web/20050627082550/http://www.npl.co.uk/optical_radiation/superblack.html
|archive-date=2005-06-27
}}
Applications of super black are in specialist optical instruments for reducing 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.{{Cite journal
|doi=10.1039/b204483h
|title=The physical and chemical properties of electroless nickel – phosphorus alloys and low reflectance nickel – phosphorus black surfaces
|year=2002
|last1=Brown|first1=Richard J. C.
|last2=Brewer|first2=Paul J.
|last3=Milton|first3=Martin J. T.
|journal=Journal of Materials Chemistry
|volume=12|issue=9
|page=2749
}}
In 2009, a competitor to the super black material, Vantablack, was developed based on carbon nanotubes. It has a relatively flat reflectance in a wide spectral range.{{cite web|url=http://www.nasa.gov/topics/technology/features/super-black-material.html |title=NASA Develops Super-Black Material That Absorbs Light Across Multiple Wavelength Bands |publisher=Nasa.gov |date=2011-11-08 |access-date=2015-07-14}}
In 2011, NASA and the US Army began funding research in the use of nanotube-based super black coatings in sensitive optics.[https://sbir.gsfc.nasa.gov/content/nanostructured-super-black-optical-materials Nanostructured Super-Black Optical Materials] 10/23/2013 {{webarchive |url=https://web.archive.org/web/20140302004316/https://www.sbir.gov/sbirsearch/detail/417149 |date=March 2, 2014 }}
Nanotube-based superblack arrays and coatings have recently become commercially available.{{cite web|url=http://www.nano-lab.com/alignedcarbonnanotubearrays.html |title=Aligned Carbon Nanotube Arrays and Forests on Substrates |publisher=Nano-lab.com |date= |access-date=2015-07-14}}
See also
References
{{Reflist}}
External links
- {{cite magazine |url= https://www.wired.com/dangerroom/2012/12/army-goth/ |magazine= Wired |title= Army Goes Goth with "'Super-Black' Materials |first= Robert |last= Beckhusen |date= December 24, 2012 }}
- {{cite journal |journal= New Atlas |url= http://newatlas.com/super-black-material/20434/ |title= NASA's new super-black nanotube-based material is good news for star-gazers |first= Darren |last= Quick |date= Nov 9, 2011 }}
- {{cite web |url= http://www.paintsquare.com/news/?fuseaction=view&id=11855 |title= Super Black Coatings on a Mission |date= August 19, 2014 |quote= Part of NASA's Materials Coating Experiment |publisher= Paint Square }}
- {{cite web |url= http://www.acktar.com/category/VacuumBlack |title= Magic Black, Vacuum Black |publisher= Acktar |work= Advanced coatings |quote= Inorganic, thin coating, deposited using vacuum deposition technology }}