Effect of Sn on Corrosion Behavior of Ultra-pure 17 mass Cr Ferritic Stainless Steels in Sulphuric Acid

摘要

The effect of Sn on corrosion behavior of ferritic stainless steels in 20 mass% H2 SO4 was investigated by alternating current and direct current electrochemical methods and gravimetric tests at 25 ℃.The results show that Sn can effectively improve general corrosion resistance of ferritic stainless steels in H2 SO4 ,mainly due to highly raised hydrogen evolution overpotential which is in favour of strong suppression of hydrogen evolution reaction,and inhibitive effect of dissolved Sn2+ on elementary anodic reactions.With increasing Sn content,the better corrosion re-sistance can be reached.The Electrochemical Impedance Spectroscopy (EIS)includes four time constants and can be perfectly fitted by equivalent circuit:Rs(CdlRct)(QadsRads(RL1(L1(RL2L2)))).