Robust ultrablack film deposited on large-curvature magnesium alloy by atomic layer deposition

A broadband absorber composed of a TiAlC/SiO₂ film stack prepared by atomic layer deposition was presented, which could be uniformly coated on magnesium alloys with large curvature, achieving an average absorption as high as 99.4% within the wavelength range from 400 to 1000 nm. An Al₂O₃/TiO₂ interlayer was deposited on magnesium alloys prior to the deposition of ultrablack films, which effectively prevented corrosion of magnesium caused by Al³⁺ and Cl⁻ by-products in the TiAlC film. With the presence of this interlayer, the ultrablack film on the surface of the magnesium alloy exhibited good adhesion and abrasion resistance. Furthermore, after undergoing damp heat and thermal cycling tests, the absorptions of the ultrablack film-coated magnesium alloys remained at 99.1% and 99.0%, respectively, which indicated that the film is promising for application in precision optics under harsh environmental conditions.