A PHOTOELECTROCHEMICAL APPROACH TO THE ENNOBLEMENT PROCESS - PROPOSALOF AN ADSORBED INHIBITOR THEORY

The open circuit potential of titanium in water may vary significantly under illumination. It has been suggested that this shift may be rela ted to light effects on the oxide film. Experiments were therefore des igned to study the effect of illumination on the corrosion potential o f titanium and platinum in fresh (pond) water. The results indicate th at the photoelectrochemical and the organic photochemical reaction inf luence the excursion of the potential during the day and night. In add ition, a negative photo-potential was observed for titanium and platin um, indicating the presence of a n-type semiconducting film, even in t he presence of biofilm on the respective surfaces. The dissolved nutri ents within the biofilm were also estimated. It is concluded that ''mi xed inhibitor'' may strengthen the n-type semiconducting oxide film on the metal surfaces during the processes of ennoblement. The results a re discussed in the context of the findings made.