Protectiveness, morphology and composition of corrosion products formed on carbon steel in the presence of Cl⁻, Ca²⁺ and Mg²⁺ in high pressure CO₂ environments

This study investigates the individual effects of chloride (Cl⁻), calcium (Ca²⁺), and magnesium (Mg²⁺) ions on the CO₂ corrosion behaviour of carbon steel in simulated CO₂ geologic storage environments (60 °C and 100 bar CO₂). The influence of the aforementioned ions was assessed over immersion times from 6 to 96 h. The corrosion product growth was monitored over this period and related to the extent of both general and localised corrosion. For each test, corrosion product morphology and chemistry were analysed using a combination of scanning electron microscopy (SEM), focused ion beam (FIB) method, energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD).