Recent advances on the influence of microstructural characteristics on corrosion resistance in H2SO4 of anodized titanium

Commercially pure titanium has been anodized with the use of a pulsed signal in unipolar regime, with 25 % of anodic contribution at low frequency (20 Hz). This anodizing regime can effectively enhance thickness and crystallinity of the barrier region directly in contact with the metallic substrate. The latter condition will be particularly advantageous for corrosion resistance enhancement in strong reducing acidic environment, as concentrated hot sulfuric acid (10 %v/v at 60 °C). Corrosion response has been investigated through the use of Electrochemical Impedance Spectroscopy (EIS) and results compared with weight-loss tests and Linear Polarization Resistance (LPR). The higher degree of crystallinity of the coating, in the interfacial region, will be found to provide an effective barrier against proton diffusion thus retarding debonding of the oxide promoted by hydrogen evolution reaction (HER).