ELECTROCHEMICAL FEATURES DURING PITTING CORROSION OF LY12 ALUMINUM ALLOY IN DIFFERENT NEUTRAL SOLUTI

• 作 者: F.H.Cao Z.Zhang Y.L.Cheng J.F.
• 机 构: Department of Chemistry,State Key Laboratory for Corrosion and Protection of Metals
• 出 处: 金属学报
• 发表日期: 2004年期
• 关键词: LY12 alum inum alloy pitting corrosion electrochemical impedance spectroscopy po

The electrochemical features of commercial airframe material, Al alloy LY12, in 0. 349mol/L neutral sodium chloride (NaCl) and sodium sulfate (Na2SO4) solutions were investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The microstructure of the as-tested samples was studied by scanning electron microscopy. The results show that the Nyquist plots of LY12 at different immersion time displayed different fe atures, indicating that the Cl- ions elevate the corrosion rate and inhibit the repassivation of a metastable pit. It also shows that the corrosion product of LY12 formed in SO2-4 solution isn't easy to dissolve, and it will cover the surface of working electrode in the electrolyte. SEM images indicate that the corrosion apparent area and pit number of LY12 in NaCl solution are greater than that in Na2SO4 solution.