Study on Iron Sulphide Inhibition and Corrosion of 80S and 110SS steels in Acid Solutions Containing H2S and CO2

摘要

Corrosion behavior and characteristics of 80S and 110SS steels were investigated in acid solutionscontaining H2S and CO2 at 45oC by the potentiodynamic polarization sweep, EIS and SEM with EDX.The EIS data fitted by ZsimpWin software were theoretically analyzed and discussed. The resultsindicated that the corrosion potential became more negative and that the corrosion current densitydecreased as the Na2S·9H2O concentration increases from 0 to 2.0wt.%, with the obvious reverse sweepcharacteristics occurring in anodic polarization branch curve in 2.0wt.% Na2S·9H2O case. Warburgimpedance characteristics of diffusion process in a low frequency region following a depressedcapacitive semi-circle in the intermediate frequency region was observed on 110SS steel with theaddition of certain Na2S·9H2O concentration. The phase angle peaks for H2S containing cases in theintermediate frequency region shifted to a low frequency direction and rised toward -90osignificantly.The amounts of S element in the “first deposition” corrosion product layer were higher than those in the“second deposition” corrosion product crystals. One corrosion model related to H2S and CO2 corrosionwas proposed..