The influence of Ca2+ on the growth mechanism of corrosion product film on N80 steel in CO2 corrosion environments

The influence of Ca2+ on the growth mechanism of CO2 corrosion products was investigated by weight loss, in situ electrochemical measurements and analysis of corrosion products. With the increase of Ca2+ concentration in solution, the crystallinity of product film, FexCa1−xCO3, weakened and gradually turned to amorphous structure, which provided less protectiveness and elevated the corrosion rate. The high concentration of Ca2+ resulted in the “unstable” growth of FexCa1−xCO3. At 10000 mg L−1 Ca2+, complicated FexCa1−xCO3 structures with different Ca content formed. The linear relation between Ca2+ concentration in solution and molar fraction of Ca in the film was also proposed.