Corrosion and passivation behaviour of 18Cr-10Ni stainless steel in in H2SO4 solutions in the presence of oxalate and tartrate anions

The influence of the oxalate and tartrate anions on the corrosion and passivation behaviour of 18Cr-10Ni stainless steel has been studied in IN H 2 SO 4 deaerated aqueous solutions by means of the potentiostatic polarisation curves. The experimental results show that both anions act as inhibitors of the stainless steel corrosion both in the active and in the passive state. Their presence in the IN H 2 SO 4 deaerated solutions determined the decrease of the corrosion rate, of the critical current density, and of the passive current density, the more, the larger the concentration. The inhibitor effects of these anions is explained by two assumptions: the specific adsorption with formation of dimers or polymeric chains of adsorbates and the possibility to form a film on the metal surface of the insoluble compounds between the oxalate or tartrate anions and the cations resulted from the stainless steel dissolution.