Abstract
Cobalt blue films were prepared on aluminum by a two-step anodic oxidation process. Aluminum plate was anodized in sulfuric acid by direct current and cobalt was deposited into the pores of the film by AC electrodeposition. The alumina film with deposited cobalt was then reanodized in a molten mixture of sodium bisulfate and ammonium bisulfate.
The surfaces of cobalt blue films formed in the bisulfate melt were porous and their X-ray diffraction patterns indicated the crystalline structure of a defective spinel, CoO·3Al2O3, which constitutes cobalt blue pigment.
