Optical Properties of ZrO2–Containing Anodic Coatings on Aluminum

Anodic oxide coatings (AOC) formed at the potentials of spark breakdowns in aqueous solutions of potassium hexafluorozirconate (K2ZrF6) contain up to 36 wt.% of Zr. The modification of ZrO2 in AOC is tetragonal. The reflection coefficients of AOC have been measured in the range 430–670 nm. After UV irradiation for a few hours the reflection coefficient decreases by several percent. The treatment of AOC in a solution containing F− and [Fe(CN)]3− ions leads to a change in the aluminum and zirconium concentrations in the surface layer and to an increase of the AOC reflectivity.