The Electrochemical Properties of Titanium (1st Report)

Measurement of Spontaneous Potentital and Corrosion of Titanium

Abstract

The reason why the spontaneous potential of titanium vibrates periodically to positive and negative directions in distilled or tap water, changing gradually to positive value with time, is that the positive and the negative ions accumulated in anodic (in pin holes of the oxide film) and cathodic (the oxide film) areas respectively, are not neutralized until they attain a certain amount in water. The spontaneous potential of titanium changes to a negative value with time in such solutions under natural aeration as HF>0.005%, HCl>10%, H₂SO₄>5%, H₃PO₄>30%, NH₄F>0.01%. On the contrary, in such solutions as of HNO₃, CrO₃, K₂Cr₂O₇ and K₂MnO₄ in acid solutions, Cu⁺⁺, Fe⁺⁺⁺, Ag⁺, it varies largely to a positive value and titanium is passivated. The corrosion rate of titanium in naturally aerated HF, H₂SO₄ or HCl solutions containing different oxidizing agents was measured.