ABSTRACT

This paper investigates the effect of calcium on the CO₂ corrosion behaviour of 1Cr carbon steel under the effect of flow. The experiments were performed in a flow loop system in 1 wt-% NaCl solution at 80°C, pH = 6.34 with initial S_CaCO3 = 2 and pCO₂ = 0.53 bar. The flow velocity was kept at 3 m s⁻¹ and the system was pressurised to 3 bar. The corrosion process was monitored with linear polarisation resistance and electrochemical impedance spectroscopy (EIS). Phase analysis of the corrosion products was obtained using X-ray powder diffraction and surface morphology was characterised with scanning electron microscopy. Results show that the flow delayed the precipitation of substitutional solid solution of Fe_0.31Ca_0.69CO₃, deferring the pseudo-passivation stage. The flow did not cause Mesa attack or localised corrosion. The protectiveness of this film was not affected by the presence of calcium and was comparable to the one of pure FeCO₃.

摘要

本文研究了钙在流动作用下对1Cr碳钢CO ₂腐蚀行为的影响。实验在流动回路系统中在 80°C、pH = 6.34、初始S _CaCO3  = 2 和 pCO ₂  = 0.53 bar 的1 wt-% NaCl 溶液中进行。流速保持在3 m s ^-1并且系统加压至3 bar。腐蚀过程通过线性极化电阻和电化学阻抗谱 (EIS) 进行监测。使用 X 射线粉末衍射获得腐蚀产物的相分析，并用扫描电子显微镜表征表面形态。结果表明，流动延迟了 Fe 置换固溶体的沉淀_0.31 Ca _0.69 CO ₃，延迟伪钝化阶段。流动没有引起台面侵蚀或局部腐蚀。这种薄膜的保护性不受钙的影响，与纯 FeCO ₃的保护性相当。