OBSERVATIONS OF LOCALIZED INSTABILITY OF PASSIVE TITANIUM IN CHLORIDESOLUTION

Measurement of the passivating current from titanium microelectrodes i n acidic chloride solution shows that the passive surface undergoes tr ansient microscopic breakdown. Such breakdown occurs well below the pi tting potential. The observed events are thought to be due to the nucl eation of corrosion pits; very few of these show evidence of propagati on, and there is no permanent propagation. The frequency at which thes e breakdown events occur is low, and the process persists for a long t ime.