Corrosion inhibition of Ti-6Al-4V alloy in sulfuric and hydrochloric acid solutions using inorganic passivators

The effect of iodate (IO3−), metavanadata (VO3−) and molybdate (MoO42−) anions on the passivation of Ti‐6Al‐4V alloy in sulfuric and hydrochloric acid solutions was studied using open‐circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS). The alloy surface was examined by scanning electron microscopy (SEM). It was found that an optimum concentration of the passivator is essential for the corrosion inhibition process. Above this concentration the rate of alloy corrosion decreases as the concentration of the passivating ion increases. Scanning electron micrographs have shown that the flawed regions present in the alloy surface were repaired in the presence of the passivator anion. The optimum concentration of each anion and its corrosion inhibition efficiency for titanium and Ti‐6Al‐4V alloy have been determined. It turned out that the corrosion inhibition efficiencies of IO3−, VO3− and MoO42− anions for the corrosion of Ti and Ti‐6Al‐4V in both hydrochloric and sulphuric acid solutions exceed 98%.