Abstract
Crevice corrosion of titanium and its alloys in 10% sodium chloride was investigated at 100Β°C with the aid of microelectrodes. Potential, pH and chloride ion concentration inside the crevice were monitored using an Ag/AgCl electrode, a tungsten microelectrode and a Ag/AgCl chloride ion selective microelectrode, respectively. The pH and Cl^β^ concentrations within the crevice were calculated from the standard potentialβpH and potentialβlog[Cl^β^] calibration curves. The effect of Mo on the crevice corrosion of titanium was also studied. The passivation behavior on the titanium and Tiβ15%Mo alloy was studied using electrochemical impedance studies. There was no apparent change in pH and Cl^β^ ion activity inside the crevice for the alloy at 100Β°C, whereas a marginal decrease in pH and increase in Cl^β^ ion concentration were observed for pure titanium. Thus pure titanium is susceptible to crevice corrosion in hot 10% NaCl solutions at 100Β°C. The chloride ion activity was found to be reduced for the alloy so that the pH inside the crevice increased. The corrosion reaction resistance (R~t~) was found to increase with the addition of Mo as an alloying element. It also increases with externally applied anodic potential. Hence, Mo is an effective alloying element, which enhances the crevice corrosion resistance of titanium.