Super Black Coating on the Commercial Black Anodized Al(6061) by Direct and Scalable CVD–Growth of Carbon Nanofibers

Abstract

Using carbon-based super black coatings on optical devices can achieve superior stray light suppression for applications in astronomy. For the first time, the work presents carbon nanofiber-based black coating on commercial anodized Al(6061), which facilitates the development of a highly effective route to directly integrate the carbon-based material on the common substrate for optical baffles. The scalable and available structural engineering effect is synergized with the anodized Al(6061) coating with black dye composed of nickel catalyst and the intrinsic broadband light absorption of the CVD-grown carbon material to ultimately achieve a superior broadband light absorber. Nickel catalysts embedded in anodized Al(6061) offer a practical pathway for carbon nanofiber growth through CVD without additional stacked catalysts. The CVD-growing mechanism and CNF nanostructures are demonstrated through TEM and EDS element mapping, SEM, and Raman spectroscopy. CNF-grown Al(6061) substrates offer above 99% broadband light absorption and low light reflectance below 1% in UV–vis–NIR and mid–IR ranges. This facile approach has been useful for super black coating on Al(6061)-based complicated sculptures, such as concave substrate and an optical baffle. These results have demonstrated a facile method that can significantly impact the industrial scaling-up of high-quality, super-black coating on spaceborne devices.