Abstract
The galvanic behavior of an illuminated rutile-type TiO2 and iron couple and the corrosion mass loss of the iron under the formation of this galvanic cell were investigated as a function of the hydrogen ion concentration in the aqueous solution. The rutile-type TiO2 with the form of film was formed by a high-temperature oxidation and then was reduced by a high-temperature hydrogen gas. The rest potential of the TiO2 fell due to the light irradiation. This drop increased with an increase in temperature of hydrogen reduction. The drop of the rest potential with light irradiation for the TiO2 reduced at 1173 K increased with an increase in solution pH in the aqueous solutions of pH higher than 10. In these solutions, as a result, the rest potential of the TiO2 was lower than that of the iron. When the illuminated TiO2 was in contact with the iron in the aqueous solutions of 10∼12 pH, the cathodic current passed for the iron. This current increased with an increase in the solution pH. It was found that this reason was due to that the photo-anodic current for the TiO2 increased with an increase in the solution pH. The corrosion mass loss of the iron under the formation of galvanic cell with the illuminated TiO2 was lower than that of the iron under the formation of galvanic cell with no illuminated TiO2 and that of the no galvanized iron. Further, the corrosion mass loss of the iron under the formation of galvanic cell with the illuminated TiO2 decreased with an increase in the ratio of surface area of the TiO2 to the iron.
