Porous alumina-metallic Pt/Pd, Cr or Al layered nanocoatings with fully controlled variable interference colors.

Metallic Cr, Al, and Pt/Pd alloy have been deposited by magnetron sputtering or thermal evaporation (resistance heating or electron beam heating) onto nanoporous anodic alumina and have allowed to facilitate a cost-effective technique for manufacturing of pigment-free colored coatings on aluminum. Bright and saturated colors were achieved using the interference effect, and tuned by variation of the uniform oxide film thickness. Morphology and properties of these coatings were investigated by scanning electron microscopy (SEM) and reflectance measurements (UV/Vis/NIR spectrometry).