Vantablack® an ultra-black absorptive coating for stray light control

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Super Hydrophobic Vantablack Coating

Technology abstract

 UK SME Surrey NanoSystems has developed Vantablack®, an ultra-black absorptive coating for stray light control. The coating is applied in a wide range of systems, for example as an energy absorbing coating for light/beam dumps, an absorber layer for thermal and optical sensors, and as a blackbody calibration standard. It holds the world record as the darkest man-made substance and maintains its industry-leading performance across a wide bandwidth from UV to FIR.

Technology Description

Vantablack is a thin film of carbon nanotubes (CNTs) directly 'grown' on the surface of a substrate (or object) in a reactor chamber. A unique process allows CNTs to be grown at much lower temperatures, enabling their use on a very wide range of substrates.
 
Vantablack has been successfully applied to a number of materials including; aluminium sheet/foil, aluminium oxide, aluminium nitride, aluminium alloys (6000,7000 series), cobalt, copper, molybdenum, nickel, quartz, sapphire, silicon & silicon dioxide, stainless steel, titanium and titanium nitride.
 
Applying Vantablack
The process used to grow Vantablack allows deposition on stable substrate materials with melting points above 450°C. (NB: the alternative spray-on version Vantablack S-VIS lowers this temperature requirement to 100°C.)
 
Vantablack is applied in a similar way to conventional thin-films. It can be applied directly to the product, including those with complex three-dimensional shape, or used to coat tiles or flexible foils for subsequent assembly into the final product.
 
The fine nanometre-sized optical cavities that make Vantablack so dark mean it cannot be used in environments open to direct contact and mechanical abrasion. It needs to be protected from accidental touching, for example behind or inside a component, or situated where contact is avoided.
 
Applying Vantablack S-VIS
Vantablack S-VIS is a sprayable version, so it can be applied under controlled conditions in air (enclosed & filtered spray booth). The coating is built up over a number of passes until the correct thickness has been achieved. The applied coating then passes through a number of chemical functionalisation steps to bind it together and change its density. These processes typically take place from 100°C to 300°. The spray coating can be successfully applied to most engineering materials that are thermally stable at these temperatures.
 

Innovations & Advantages

Vantablack

  • World’s darkest manmade substance
  • Total hemispherical reflectance 0.036% at 700nm
  • Excellent BDRF performance
  • Low temperature coating process at 430⁰C
  • Does not outgas
  • Extremely resilient to shock and vibration
  • Wide operating temperature range -196⁰C to 400⁰C
  • Can be optimised for Lambertian or specular reflectance
  • Non-ITAR

 
Vantablack S-VIS

  • The world’s blackest paint
  • Excellent performance across UV-VIS-IR
  • Excellent BDRF performance
  • Low temperature coating process 100⁰C
  • Does not outgas
  • Extremely resilient to shock and vibration
  • Wide operating temperature range in air and in a vacuum

Further Information

Vantablack:

  • Temperature range in air: -196ᵒ to 300ᵒC
  • Temperature range in vacuum or inert atmosphere: -196ᵒC to 1000ᵒC
  • Temperature cycling: 25ᵒC to 175ᵒC (MIL STD 810G Paragraph 501.5)
  • Temperature shock: 100ᵒC/min (-196ᵒC to 200ᵒC)
  • Shock resistance: 100-1000 Hz, 20-2000g
  • Vibration resistance: 20-2000 Hz Peak 70 g2/Hz @ 400Hz
  • Humidity resistance: MIL STD 810 G Paragraph 507.5 60ᵒC 85-95%
  • Mass / substrate area: 0.2 mg/cm2
  • Abrasion resistance: Low resistance to direct impact or abrasion

 
Vantablack S-VIS:

  • Temperature range in air: -196ᵒ to 400ᵒC
  • Temperature range in vacuum or inert atmosphere: -196ᵒC to 700ᵒC
  • Thermal Shock: -196° to 200°C temperature swing over 5 minutes
  • Shock resistance: MIL STD 810 G Method 516.6
  • Vibration resistanc:e MIL STD 810 G Method 514.6
  • Humidity resistance: Hydrophobic
  • Mass / substrate area: 0.7 mg/cm2
  • Abrasion resistance: Low resistance to direct impact or abrasion

Current and Potential Domains of Application

Potential:

  • Infrared cameras and sensors – Stray light, cold shields, IR sensors, baffles, lens barrels
  • Electro-optical systems – Stray light baffles, apertures, housings
  • Satellite systems – Cavity blackbodies, star-tracker baffles, thermal control
  • Metrology – Stray light and calibration standards for interferometers, spectrometers
  • Digital cameras & Astronomy - Stray light control, apertures, lens barrels, housings
  • Mobile telephones - Camera apertures & aesthetic styling
  • Automotive- Cameras and HUD systems, instrument panels
  • Digital projection- DMD shutters, light dump, baffles, stray light control
  • Watchmaking and jewellery - Dials, bridges, unique aesthetic design features
  • Art, design and architecture- Unique visual design features, thermal control
  • Solar energy systems- High efficiency solar absorption coatings