Corrosion behavior of coating with plasma sprayed 8YSZ on the surface of carbon steel

The corrosion behavior of plasma sprayed 8YSZ (ZrO2 stabilized by 8 wt.% Y2O3) coating on the surface of carbon steel in seawater was investigated. The electrochemical impedance spectroscopy was used as a non-destructive evaluation technique to monitor the protection properties of the coating when it was immersed in seawater, and corrosion products were characterized by scanning electron microscopy, energy dispersive spectrometry and X-ray photoelectron spectroscopy. The results indicated that three time constants were obtained during the initial immersion period, and then a new time constant appeared due to the formation of rust layer, which was corresponding to the corrosion process. Corrosion products were formed on the coating surface as well as inside the coating, and the crystalline composition of the rust layer mainly consisted of γ-FeOOH.