Corrosion Mechanism Differences of Tinplate in Aerated and Deaerated Citric Acid Solution

摘要

The corrosion behavior of tinplate in 0.1mol/L citric acid solution in aerated and deaerated conditions,respectively, were studied by a combination of electrochemical impedance spectroscopy (EIS),inductively coupled plasma (ICP) and scanning electron microscopy (SEM). Differences between thecorrosion mechanisms in the two cases were analyzed. Under aerated conditions, three stages weredistinguished during the corrosion process: the corrosion of tin coating, the corrosion of the carbonsteel and the detachment of the surface corrosion product. ICP results showed that the Sn content in thesolution increased at the early stage and then basically remained stable, while the Fe content increasedcontinuously up to 184ppm. Under deaerated conditions, the corrosion process of tinplate wasdominated by the anodic dissolution of the tin coating, and ICP analysis showed that the changingtrend of Sn content in the solution resembled that of the aerated case while the Fe content kept verylow. The corrosion mechanisms under the two conditions were therefore proved different.