Pitting of Titanium

Experiments were conducted in which pitting occurred at the edges and on the circumference of holes in titanium foil in chloride, bromide, and iodide solutions under potentiostatic conditions. Valence of dissolution was approximately 4. The effect of potential, temperature, concentration, p H, and solution flow on current density and pitting potential was determined. Very complex behavior not fitting a single kinetic, mass transport, or ohmic limitation was observed. A model combining a salt film on the metal surface with events in the electrolyte diffusion layer qualitatively fits the data.