Pitting corrosion evaluation of titanium in NH₄Br solutions by electrochemical methods

Anomalous pitting sensitivity of titanium in ammonium bromide solutions was detected. Under saturation conditions pitting was not observed visually after anodic polarization and positive hysteresis loop was not recorded. Electrochemical impedance spectroscopy (EIS) shows an increase in resistance with time without an inductive element in the equivalent electrical circuits. This anomalous behavior may be related to changes in the molecular structure of the OH^- bonds under saturation. In dilute ammonium bromide solutions, a pitting attack was observed visually after anodic polarization and cyclic polarization had shown a positive hysteresis loop. EIS shows an inductive loop related to the active pits that exist on the anodic surface.