The Coloring Mechanism of Boehmite-treated Aluminum Foil

Abstract

Boehmite-treated aluminum foil was colored by a platinum coating, and its mechanism of coloring was investigated. Hydrated aluminum (boehmite (Al00H)) was generated on the surface of aluminum foil. The color of the boehmite-treated surfaces did not change the metallic luster of the aluminum foil surface with treatment time. However, when the boehmite-treated aluminum foil surfaces were coated with platinum by magnetron sputtering, the color of the surface changed to several different colors based on the hydration time. This coloring mechanism was investigated by observation of surface structures and simulations of the reflectance of multilayer film interference. Boehmite develops as a porous needle shaped film on the aluminum surface. The deposited platinum coating is deposited in a similar manner. Therefore, the coloring mechanism of the boehmite films is thought to be due to the interference of multilayer films with varying degrees of thickness.