Coloring the Layer Thickness of Anodized Aluminum by Integral Color Process


The identification of the self coloring process in anodizing process is integral color. In this research specimens of pure aluminum (1000) and AA 5056 anodized by using Alternative Current (A.C) techniques were investigated under standard conditions and electrolytically colored in sulfuric acid baths solutions at different operating conditions [Alternative Current density (A.C) (2-3) Amp/dm2, electrolyte concentration (2-6) Normality, electrolyte temperature (15-25) Co and anodizing time (20-60) minutes]. The experimental work was designed according to (Box-Wilson) method by using second order polynomial model between four variables and thickness of anodic layer for the two types of materials and substituted the experimental results for anodizing process in proposed model to calculate the coefficients of the mathematical equations to find an expression for obtaining best film thickness. The coloring deposition efficiency increases with the increase of applied electrolytic coloring alternative current and the purity of aluminum. Under standard electrolytic coloring conditions, the current efficiency for coloring deposition is low for all examined materials. However, pure aluminum has much higher coloring deposition efficiency than the alloy. The anodizing alternative current density affects the electrolytic coloring process to a lesser degree for alloy than for pure aluminum, indicating the role of the morphology of the oxide film. The increases of anodizing temperature and porous layer thickness have marginal effect on electrolytic coloring process. Understanding the effect of alloy types on electrolytic coloring process will enable us to achieve color uniformity and to expand color and shade selections.