Impedance analysis on the structural evolution of NaCl-induced corrosion products formed on pure titanium

This study employed electrochemical impedance spectroscopy (EIS) to investigate the evolution of pore structures within the NaCl-induced corrosion-affected zone. When a small amount of NaCl was deposited, mesopores within the matrix initially formed and were subsequently repaired by the growth of oxides. The amount of NaCl promoted the formation of mesopores by accelerating the destruction of the oxide layer and Cl-induced active corrosion. A transmission line model (TLM) was proposed for the studied porous titanium electrode. The high-frequency slope of the Nyquist plot can monitor the mesopores formation, which are the positions for stress corrosion crack initiation in titanium alloys exposed to NaCl-containing environments. The angle between the Nyquist plot and the real axis was less than 31° when the abundant mesopore formed.