Hemispherical reflectance and emittance properties of carbon nanotubes coatings at infrared wavelengths

Abstract

Recent visible wavelength observations of Multiwalled Carbon Nanotubes (MWCNT) coatings have revealed that they represent the blackest materials known in nature with a Total Hemispherical Reflectance (THR) of less than 0.25%. This makes them exceptionally good as absorbers, with the potential to provide order-ofmagnitude improvement in stray-light suppression over current black surface treatments when used in an optical system. Here we extend the characterization of this class of materials into the infrared spectral region to further evaluate their potential for use on instrument baffles for stray-light suppression and to manage spacecraft thermal properties through radiant heat transfer process. These characterizations will include the wavelength-dependent Total Hemispherical Reflectance (THR) properties in the mid-and far-infrared spectral regions (2-110 μm). Determination of the temperature-dependent emittance will be investigated in the temperature range of 40 to 300 K. These results will be compared with other more conventional black coatings such as Acktar Fractal Black or Z306 coatings among others.

Vertically aligned carbon nanotubes black coatings from roll-to-roll deposition process

“…In agreement with literature data on the reflectance of VACNTs [3,4,5], the total hemispherical reflectance is below 2% and the specular reflectance is below 0,02% for most samples at wavelength above 400nm. This confirms the diffusive behaviour of VACNTs as a very low reflectance coating.…”

Evaluation of optical properties of CMK-1 and CMK-3 mesoporous carbons and introduction them as very interesting black pigments

“…Since carbon has a relatively high index, will require very low density of mesoporous carbons so that the boundary does not produce a large reflection. Bulk carbon is black but very shiny due to its high index [24].…”

“…Stray light is controlled by utilizing low reflectance structural surface treatments and by using baffles and stops to limit this background noise. Development of this technology will provide numerous benefits including the increase in observational fidelity by reducing scattered light in high contrast regions [24]. To receive the above purposes and produce an excellent black body, we suggested utilizing of the mesoporous carbons in black coatings for the first time.…”

Spectral selectivity in infrared thermal detection

“…These coatings were utilized as absorbers for large area pyroelectric detectors 54 and for reducing stray light in space borne instruments. 55,56 Antiresonant interference structures Antiresonance structures employ a quarter wave gap between a bottom reflector and the detector to couple a broadband signal into the absorbing bolometer. The bottom mirror is usually metallic.…”