An attempt was made to develop an electrolytic method to color anodized aluminum white by depositing hydrated titanium oxides in pores in the anodic oxide film by electrophoresis. The objective of this study is to determine the optimum process parameters which give sufficient whiteness to anodized aluminum.
It was found that the whiteness depends significantly on the anodizing process. Sufficient whiteness was not obtained on the aluminum which anodized in sulfuric acid bath, while sufficient whiteness was obtained on the aluminum which is anodized in two acids : first in sulfuric acid bath and then in phosphoric acid bath. It appears that the stronger whiteness in the latter process is due to the formation of the larger pore size in the anodic oxide film which allows sufficient amount of hydrated titanium oxide particles to deposit in the pores.
It was found from the polarization curve that the deposition of titanium oxide on the anodic oxide film takes place at about -3
V- -3.5
V. More homogeneous whiteness was obtained by A. C. electrolysis at about 16
V than by D. C. electrolysis at -3- -3.5
V.
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