Effect of Oxygen on CO_2 Corrosion and Erosion-Corrosion Behavior of N80 Steel under High Temperature and High Pressure

摘要

The role of O_2 in CO_2 corrosion and erosion-corrosion was investigated using high temperature and high pressure autoclaves, more research methods of material surface such as SEM, XRD, and EDS etc. were used. The results suggested that under static conditions, the corrosion morphology of pure CO_2 was uniform corrosion, and when O_2 was added, it translated into pitting corrosion and the corrosion rate increased. Fe_2O_3, Fe_3O_4, and FeCO_3 were the main corrosion products in CO_2-O_2 environments. The potentiodynamic sweeps results showed that when O_2 was added, the corrosion potential increased by 41mV vs. Ag/AgCl and the corrosion current density increased by 300%. When the flow velocity increased to 2 m/s, the corrosion rate of the two corrosive environments both had a significant increase. Moreover, when sands were also added, the CO_2-O_2 erosion-corrosion rate with sands was remarkably increased, which indicated that the presence of O_2 made the synergy of corrosion and erosion largely enhanced.