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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 Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''P ...
paint Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...
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 Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other type ...
a
nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...
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phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
alloy An alloy is a mixture of chemical elements of which in most cases at least one is a metal, metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Metallic alloys often have prop ...
. Applications of super black are in specialist
optical instruments An optical instrument is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and determine their characteristic properties. Common examples include periscopes, microscopes, telescopes, and cameras ...
for reducing unwanted reflections. The disadvantage of this material is its low optical thickness, as it is a surface treatment. As a result,
infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
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. In 2009, a competitor to the super black material, Vantablack, was developed based on
carbon nanotubes A carbon nanotube (CNT) is a tube made of carbon with a diameter in the nanometre range (nanoscale). They are one of the allotropes of carbon. Two broad classes of carbon nanotubes are recognized: * ''Single-walled carbon nanotubes'' (''SWC ...
. It has a relatively flat reflectance in a wide spectral range. In 2011, NASA and the US Army began funding research in the use of nanotube-based super black coatings in sensitive optics. Nanotube-based superblack arrays and coatings have recently become commercially available.


See also

* Vantablack *
Emissivity The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation that most commonly includes both visible radiation (light) and infrared radiation, which is n ...
*
Black hole A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...
* Black body


References


External links

* * * * {{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 Materials science Optical materials Shades of black