Corrosion protection of Fe (100) in supercritical CO2 achieved by applied electric field: A ReaxFF molecular dynamics study

The corrosion damages induced by supercritical CO2 (SCO2) in Brayton cycle make the iron-base alloy equipment suffer a lot, which seriously affects the operation performance of the system. In this study, the corrosion mechanism of Fe (1 0 0) in SCO2 under applied electric field was explored by us. The corrosion reaction process was observed, and the change of oxide layer thickness and consumption of SCO2 molecule on Fe (1 0 0) under different applied electric field directions and intensities were investigated by ReaxFF molecular dynamics simulation. The results indicate that the oxidation can be promoted by applied electric field along Z of the system direction, in which the reaction degree is 1.21 times that without applied electric field. However, the applied electric field along -Z and X direction of the system can inhibit the corrosion, in which the reaction degrees are 0.50 and 0.56 times that without applied electric field, respectively, and the Fe atoms on the surface are fixed and the subsequent reaction is prevented under the electric field along X direction. It is also found that the anticorrosion effect of oblique applied electric field is more significant than that of applied electric field along -Z or X directions. In addition, as the applied electric field intensity along Z direction increases, the reaction degree is promoted, the upper part of Fe atoms goes through the process of oxidation first and then partial reduction. But as the applied electric field intensity along -Z or X directions increases, the corrosion can be significantly prevented.

Automated summary

This study explored the corrosion mechanism of Fe (100) in SCO2 under applied electric field. The results showed that the direction and intensity of the electric field can influence the corrosion process. The electric field along Z direction promotes the oxidation reaction, while the electric field along -Z and X directions inhibits corrosion. The anticorrosion effect of oblique applied electric field is the most significant.