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Influence of CO2 subcritical and supercritical pressures on the protective properties of corrosion product scales formed on X65 steel

2024; Elsevier BV; Volume: 206; Linguagem: Inglês

10.1016/j.supflu.2024.106184

1872-8162

Tania Regina Schmitz de Azevedo Rodrigues, Juliane Bernardes Marcolino, Martimiano K. Moraes, Natália Feijó Lopes, Eleani Maria da Costa,

Concrete and Cement Materials Research

The effects of subcritical and supercritical pressures in CO2-corrosion and scale properties were investigated. The corrosion of the API5L X65 steel was carried out in wet CO2 and CO2-saturated water environments at 50ºC for periods of 168 and 360 h. Corrosion rates were quantified through weight loss, while scale properties were obtained by scanning electron microscopy, X-ray diffraction, linear potentiodynamic polarization (PP), and electrochemical impedance spectroscopy (EIS) techniques. Corrosion rates were higher in CO2-saturated water (0.59-5.09 mm/y) compared to the wet CO2 environment (0.05-0.09 mm/y). Through a comprehensive analysis, it was observed that scales tended to become more compact with increasing pressure, decreasing the corrosion rate over time. Moreover, FeCO3 scales formed under supercritical pressures and in CO2-saturated water demonstrated enhanced protective properties, as evidenced by the PP and EIS results. For these environmental conditions, the polarization and charge transfer resistances reached values of 3 ×106 to 6×106 and 3×106 to 1×107Ω.cm2, respectively.