1997 Volume 46 Issue 3 Pages 176-179
To evaluate the corrosion resistance of passive film on titanium in reductive enviroment, change in electronic property of the anodic oxide film was pursuited with passage of time by using an impedance technique in neutral borate solution. When the passive film was formed at the potential noble than 6V, the surface states was induced to the film which was eliminated at the potential less noble than 0.5V. If the electrode potential was set at potentials less noble than -0.5V, hydrogen penetration would occur to transform the film composition from TiO2 to TiOOH with reducing electric resistivity of the film. If the potential was held between 0.0V and -0.5V, the gradual reduction of space charge layer thickness was observed. Although TiO2 is considered to be stable from the view point of thermodynamics, the result suggests that the change such as hydration of the film may occur.