Effect of Inorganic Anions on the Pitting Behaviour of Austenitic Stainless Steel 304 in H2SO4 Solution Containing Chloride Ion

The effect of addition of inorganic anions, silicate, periodate and permanganate on the pitting behavior of stainless steel 304 in 0.5M H2SO4 containing 0.1M NaCl was studied using electrochemical impedance spectroscopy ( EIS) and potentiodynamic polarization techniques. In the absence and presence of silicate ion, the peak characteristic for the reduction of sulphate ion was clear in the potentiodynamic polarization curve. This peak was also present in presence of low concentrations of periodate or permanganate but disappeared at high concentrations of both anions. This indicates that periodate or permanganate ions possess a great pitting inhibition at high concentrations, this was also confirmed by EIS technique.