Effect of Ca on corrosion resistance of corten steel sections under marine atmospheric environment

Recent studies have shown that the addition of trace Ca into corten steel sections can not only effectively avoid the harmful phenomena such as rust slurry hanging during its use, but also improve the overall atmospheric corrosion resistance of corten steel sections. In the electrolyte film formed on the corten steel sections surface, trace Ca can combine with O and S elements to form CaO and CaS and dissolve in it, which enhances the alkalinity of corrosion interface, transforms the rust layer into a dense α-FeOOH, and improves its corrosion resistance.

After simulating the cyclic corrosion of ocean atmosphere, two rust layers were formed inside and outside the corten steel sections. The rust layers were porous and consisted mainly of γ-FeOOH and β-FeOOH. The addition of Ca in corten steel sections promotes the formation of α-FeOOH in the inner rust layer, which makes the inner rust layer have compact structure and prolongs the corrosion period.

The combined use of Ca and Si in corten steel sections was found to be the best through cyclic corrosion test in simulated marine environment and atmospheric exposure test in real marine environment. The results show that CaOx SiO 2 or CaOx Al2O3 2SiO2 are formed by Ca and Si. Acidic SiO2 can reduce the alkalinity of CaOx and reach the ideal pH value of protective α-FeOOH formation, thus improving the corrosion resistance of corten steel sections.