Study of In-situ electrochemical corrosion behavior and microscopic corrosion mechanisms of X80 pipeline steel in a supercritical CO2 environment

摘要

The present study conducted an in-depth investigation of the electrochemical corrosion behavior and microscopic corrosion mechanisms of X80 steel under a supercritical CO2 (sCO2) environment at 60° C and 9 MPa. Building upon the traditional three-electrode setup, the researchers innovatively designed two novel in -situ electrochemical testing circuits, one under a CO2-enriched environment and the other under a H 2O-enriched environment. Through electrochemical impedance spectroscopy, the study revealed the distinct differences in the interfacial corrosion of X80 steel under the CO 2-enriched and H 2O-enriched environments, which corresponded to the varying corrosion conditions within different regions of the pipeline. Coupled with the analysis of surface evolution, the study provided a detailed elucidation of the deposition and development mechanisms of the corrosion products. Furthermore, the researchers employed micro -scale density functional theory (DFT) calculations to explore the three-step hydrolysis mechanism of sCO2 on the Fe surface and the potential formation pathways of the FeCO3 product, which offered valuable theoretical insights into understanding the corrosion behavior of carbon steel under the supercritical CO2 environment.