Corrosion resistance testing of some binary titanium alloys in HC1 solutions

Abstract

The corrosion resistance testing of two binary titanium alloys (Ti-15Mo and Ti-32Mo) in comparison with the base metal, in hydrochloric acid solutions is reported. The anodic potentiostatic curves for the binary alloys differ from that of the base metal: Ti-15Mo alloy exhibits an active-passive range with higher critical passivation and passive current densities than titanium; Ti-32Mo alloy does not reveal active dissolution range but a higher passive current density than that of Ti. The binary alloys have lower corrosion rates than the base metal, especially at high HCl solution concentrations and temperatures. The impedance spectra were fitted with a three time constants equivalent circuit: one time constant is for the double layer capacity (C-dl) and the passive film resistance (R-p), another time constant is for the charge transfer reactions visualised by a constant phase element (CPE) and a resistance (R-1) in parallel, and the third time constant is for diffusionprocesses represented by a resistance (R-2) and a Warburg (W) element in parallel.