Effect of calcium ions on CO₂ corrosion of 3Cr low-alloy steel

Zhijun JIA,Cuiwei DU,Zhiyong LIU,Jin GAO and Xiaogang LI Corrosion and Protection Center,University of Science and Technology Beijing,Beijing 100083,China

摘 要：The effect of calcium ions on the corrosion behavior of 3Cr low-alloy steel in CO 2 containing sodium chloride solution was investigated by immersion test and electrochemical measurements. It is found that with the addition of Ca 2+ to CO 2-containing solution,the crazing level of the corrosion scale on the specimen is much slighter than that of the specimen immersed in solution without Ca 2+ . The pitting on the surface of the specimens immersed in the solution with Ca 2+ is relatively small and distributes uniformly all over the surface. The significant change in the anodic polarization curve is attributed to the deposition of the CaCO 3 . CaCO 3 deposits on the specimen surface and gives a protection to the metal substrate. And with the anodic proceeding,the concentration of H + in the solution increases. The CaCO 3 deposition dissolves in the low pH solution and the protection effect disappears.

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