Effect of FeCrAl Sublayer Composition on the Microstructure and Corrosion Resistance of FeCrAl/yttria-stabilized Zirconia Composite Coatings

The effect of FeCrAl sublayer composition on the microstructure and lead-bismuth eutectic corrosion behavior of the FeCrAl/YSZ (Yttria-stabilized zirconia) composite coatings was systematically investigated by SEM and XRD. The results show that the FeCrAl sublayer as a diffusion barrier and a bonding layer is beneficial to improve the corrosion resistance of the coatings. After corrosion, a slow-growing, continuous, and protective Al-rich oxide is formed at the interface between the YSZ and FeCrAl sublayer, which effectively hinders the inward diffusion of oxygen atoms and the outward diffusion of iron atoms. Especially, the Fe-12Cr-7Al/YSZ coating exhibits the best corrosion resistance even after corrosion at 700 °C. The microscopic corrosion mechanism of FeCrAl/YSZ coatings is elucidated.