Thickness of anodic titanium oxides as a function of crystallographic orientation of the substrate

This work deals with the anodization-driven oxidation of titanium, studied as a function of the crystallographic orientation of the crystal grains of the substrate. On a polycrystalline surface, different colors appear on the surface after anodization under galvanostatic conditions at a fixed potential. The color of the oxides on individual grains is correlated to an independent set of reflectometry data relating color to thickness, to infer the approximate thickness of the oxide layer grown on each grain in the polycrystal. These data are further related to the crystallographic orientation of each grain as assessed by electron backscatter diffraction measurements. It is shown that crystallographic orientations close to (0001) lead to relatively slower oxidation as compared with inclined orientations