Influence of Nano-CeO2 on the Corrosion Resistance of PTFE/PEEK Coatings Prepared by Electrostatic Powder Spraying Technique

Polytetrafluoroethylene/Polyetheretherketone (PTFE/PEEK) corrosion-resistant coatings were prepared on the surface of 7075 aluminum alloy by the electrostatic powder spraying technique (EPST). To achieve a denser microstructure and improved hydrophobic properties, we introduced nano-CeO2 to fill the coatings and analyzed the mechanism of its effect on the different coating structures. The corrosion resistance of the coatings was evaluated using NaCl immersion. The results indicate that nano-CeO2 enhances the coatings by filling local defects and forming a denser microstructural barrier, thereby improving the hydrophobicity and corrosion resistance of the composite coatings. Additionally, the addition of nano-CeO2 to the 20 µm PTFE/PEEK composite coating increases structural heterogeneity and pore defects, reduces coating densification, and facilitates the penetration of corrosive media, thereby weakening the barrier capability of the coating. However, in the 50 µm PTFE/PEEK/CeO2 composite coating, nano-CeO2 particles fill part of the pre-existing defects and improve coating densification, thereby increasing the resistance to the penetration of corrosive media through the coating. This enhanced barrier effect delays the contact of corrosive media with the substrate and improves the corrosion resistance of the coating. In this study, the 50 μm PTFE/PEEK/CeO2 composite coating with a nano-CeO2 content of 0.5 wt.% exhibited the best corrosion resistance, with a corrosion current density of 8.02 × 10−4 μA·cm−2, while |Z|0.01Hz remained above 106 Ω·cm2 after 720 h of immersion in NaCl solution.