None more black: UK engineers create world's darkest material
A radiation-absorbing material developed for space-based applications is finding new applications closer to home.
Vantablack, a so-called ‘super black’ coating from Surrey Nanosystems, combines exceptionally low mass, thermal stability and an ability to absorb 99.96 per cent of incident radiation. Consequently, the coating is suited to applications including apertures, baffles, cold shields and Micro Electro Mechanical Systems (MEMS)–type optical sensors.
The material also overcomes limitations encountered in the manufacture of super-black carbon nanotube-based materials, where high temperatures precluded direct application to sensitive electronics or materials with relatively low melting points. This, along with poor adhesion, prevented their application to space and airborne instrumentation.
The material, a vertically aligned nanotube array, is borne out of applying the company’s patented low-temperature carbon nanotube growth process to develop a material for space-based black body calibration sources for Earth observation.
Ben Jensen, CTO Surrey NanoSystems told The Engineer: ‘It meant essentially transferring our technology that we’d developed for growth on silicon at low temperatures to aluminium flight qualified type materials, such as 6061 type substrates.
‘As part of that process the material not only had to perform to the existing standard materials such as Martin Enhanced Black, it had to be able to suffer the rigours of launch, staging, and long-term use in space.
‘Fortunately, it was incredibly successful. We’d developed a material that turned out to be better - by a large margin - than anything that had been used before, and was spectrally flat in critical regions used in Earth observation.
‘We then proceeded to go through standard space qualification tests at independent labs, so…the material was sent out for shock and vibration, thermal vacuum, outgassing, mass loss – all the tests that are absolutely critical for any coating that is used near sensitive instrumentation in space.
‘What came out of that is…a number of terrestrial and airborne applications that can benefit from this type of material, and those were things that we had no idea of at the time.’
For terrestrial applications the material can be applied to any instrument where light suppression is critical. Jensen added that the material is tuneable across a range of wavelengths, so if the application requires very good suppression in the mid-infrared it is possible to tune the material to give optimum performance in that area.
The coating, which has also achieved European Cooperation on Space Standardisation (ECSS) accreditation, can be applied to flat and three-dimensional structures in precise patterns with sub-micron resolution.
The Newhaven-based company is now scaling up production to meet the requirements of its first customers in the defence and space sectors.