Corrosion of titanium in acid medium

International audienceThe behaviour of titanium electrodes in sulphuric acid solutions (0.5 M and 5 M) has been studied by means of potential decay curves at open circuit potential and impedance spectroscopy measurements. Indeed, in these media, the dissolution of TiO2 always occurs but it may be counter-balanced by the passivation of the electrode (formation of a TiO2 layer) if oxidizing species are present in the solution (dissolved oxygen). Corrosion of the metal is not observed in 0.5 M solutions but it occurs in the most concentrated solutions.On the contrary, if a sufficient amount of supplementary oxidizing species (chromate or nitrate) is added to concentrated sulphuric acid solutions, inhibition of the corrosion is observed. From these results, it was possible to understand the deactivation process of Ti/TiO2-IrO2 Dimensionnaly Stable Anodes (DSAs). In addition, it was concluded that it will be possible to use Ti/TiO2/PbO2 electrodes as low cost DSAs for the oxidation of Cr(III) into Cr(VI) in concentrated sulphuric acid for the regeneration of Cr(VI)