Effect of CeO₂ content on the corrosion resistance of nanostructured Al₂O₃-10wt.%TiO₂ ceramic coatings

Nanostructured Al₂O₃-10wt.%TiO₂-nCeO₂ ceramic coatings (where n is 0 wt.%, 0.2 wt.%, 0.5 wt.%, and 0.8 wt.%) were prepared on a 304 stainless steel substrate using atmospheric plasma spraying. The phase composition and microstructure of the coatings were characterized using an X-ray diffractometer and a scanning electron microscope. The corrosion resistance of the coatings was assessed through electrochemical experiments and chloride ion corrosion tests. The results indicated that the coatings comprised both partially and fully melted regions, with spherical particles and pores present on the coating surfaces. The incorporation of CeO₂ enhanced the melting of the sprayed powder during the spraying process. When the CeO₂ content was 0.2 wt.%, the melting of the sprayed powder was optimal. The porosity of the coating was minimized to 2.45%. CeO₂ also positively influenced the grain refinement of the coating; at 0.2 wt.% CeO₂, the grain size was at its minimum. The grain size of this coating was calculated to be 21.135 nm using the Scherrer formula. This coating demonstrated the best corrosion resistance, with a corrosion potential of −596.31 mV and a corrosion current density of 1.65 × 10⁻⁶ A/cm², resulting in a weight loss of 0.0170 g due to chloride ion corrosion.