Corrosion Properties of 316L Stainless Steel with Electroplated Pd Coating in Dilute Sulfuric Acid with High Concentration of SO^2-₄ at High Temperature

A thin Pd film was deposited on the 316L stainless steel sample by electroplating. Polarization measurement, electrochemical impedance measurement and weight loss test were conducted to study the corrosion resistance of 316L SS with Pd film in a 10% H2SO4 + 250 g/L Na2SO4 + 16 g/L ZnSO4 solution (94 ℃). The results showed that the corrosion potential was greatly inereased by 700 mV, and the surface passivation was promoted, so the corrosion resistance of the steel was improved. When the solution contained some concentrations of Cl- (from 100 mg/L to 1000 mg/L), the corrosion potential of the steel sample with Pd film was still in the passivation range of 316L SS, the impedance was decreased and the corrosion rate was lower apparently compared with that of 316L SS, indicating that the 316L SS steel could remain very good corrosion resistance under the Cl- condition after electroplated with Pd film.