Micropitting of Titanium during Anodic Oxidation in Formic Acid

Abstract

THE anodic oxidation of titanium in the majority of electrolytes (sulphuric, phosphoric, boric acid, etc.) results in the formation of a thin homogeneous dielectric oxide film of titanium dioxide (amorphous or crystalline). At constant current the potential increases with increasing film thickness, and, if the potential is then maintained constant, the ionic current decreases rapidly and the current becomes almost entirely electronic. In these circumstances, providing film breakdown does not occur, film growth practically ceases and oxygen evolution becomes the predominant electrode process.