Sensitive electro-optical imaging and target-acquisition systems will achieve new levels of range and sensitivity performance thanks to a UK company’s breakthrough in developing a ‘super black’ material to be launched at the Farnborough International Air Show.
Surrey NanoSystems’ Vantablack® is revolutionary in its ability to be applied to light-weight, temperature-sensitive structures such as aluminium whilst absorbing 99.96% of incident radiation, believed to be the highest-ever recorded.
“Vantablack is a major breakthrough by UK industry in the application of nanotechnology to optical instrumentation. For example, it reduces stray-light, improving the ability of sensitive telescopes to see the faintest stars, and allows the use of smaller, lighter sources in space-borne black body calibration systems. Its ultra-low reflectance improves the sensitivity of terrestrial, space and air-borne instrumentation”, said Ben Jensen, Chief Technology Officer, Surrey NanoSystems.
Carbon nanotubes are incredibly absorbent across a huge range of spectra, from ultraviolet, to visible light, to infrared, to microwaves. Vantablack will be a very good material for stealth aircraft, weapons, and many other military uses. It will also be used on the inside of telescopes and other imaging devices, where absorbing stray radiation can significantly reduce the amount of noise — and thus increase the effective range and resolution).
The fabrication of NanoTube Black, a Vertically Aligned carbon NanoTube Array (VANTA) on aluminium substrates is reported for the first time. The coating on aluminium was realised using a process that employs top down thermal radiation to assist growth, enabling deposition at temperatures below the substrate’s melting point. The NanoTube Black coatings were shown to exhibit directional hemispherical reflectance values of typically less than 1% across wavelengths in the 2.5 µm to 15 µm range. VANTA-coated aluminium substrates were subjected to space qualification testing (mass loss, outgassing, shock, vibration and temperature cycling) before their optical properties were re-assessed. Within measurement uncertainty, no changes to hemispherical reflectance were detected, confirming that NanoTube Black coatings on aluminium are good candidates for Earth Observation (EO) applications.
Vantablack is the result of applying Surrey NanoSystems’ patented low-temperature carbon nanotube growth process to the UK Technology Strategy Board’s ‘Space for Growth’ programme, working alongside the National Physical Laboratory and Enersys’ ABSL Space Products division. The manufacture of `super-black` carbon nanotube-based materials has traditionally required high temperatures, preventing their direct application to sensitive electronics or materials with relatively low melting points. This, along with poor adhesion, prevented their application to critical space and air-borne instrumentation. The two year development and test programme was completed in December 2013, during which period Surrey NanoSystems successfully transferred its low-temperature manufacturing process from silicon to aluminium structures and pyroelectric sensors. As part of the programme, qualification to European Cooperation on Space Standardisation (ECSS) standards was also achieved.
Vantablack has the highest thermal conductivity and lowest mass-volume of any material that can be used in high-emissivity applications. It has virtually undetectable levels of outgassing and particle fallout, thus eliminating a key source of contamination in sensitive imaging systems. It withstands launch shock, staging and long-term vibration, and is suitable for coating internal components, such as apertures, baffles, cold shields and Micro Electro Mechanical Systems (MEMS) –type optical sensors.
“We are now scaling up production to meet the requirements of our first customers in the defence and space sectors, and have already delivered our first orders. Our strategy includes both the provision of a sub-contract coating service from our own UK facility, and the formation of technology transfer agreements with various international partners”, said Jensen.
As a spin-off from its work in applying nanomaterials to semiconductor device fabrication, Surrey NanoSystems’ manufacturing process also enables Vantablack to be applied to flat and three-dimensional structures in precise patterns with sub-micron resolution. Vantablack is manufactured using Surrey NanoSystems’ NanoGrowth®-Catalyst systems at the company’s state of the art R&D centre in East Sussex, UK.