THE EFFECTS OF POLARIZATION POTENTIAL AND CONCENTRATION OF HYDROCHLORIC-ACID ON THE PHOTOPOTENTIAL OF PASSIVE FILMS FORMED ON TITANIUM IN HYDROCHLORIC-ACID SOLUTION

The effects of polarization potential and concentration of hydrochloric acid on the photopotential of the passive film formed on titanium in hydrochloric acid solutions were investigated. The photopotentials measured for titanium at open circuit condition after potentiostatic polarization at potentials in the passive region showed negative values, and increased in the negative direction with an increase in polarization potential. The increase in concentration of hydrochloric acid for the solution led to an increase in passive current density and a lowering of the photopotential. The results were interpreted on the basis of Oshe's model, and discussed from the viewpoint of semiconductor properties of passive film. © 1990.