Cu‐Doped Phosphate Coating: Antibacterial and Biocorrosion Resistance Against P. aeruginosa in Simulated Seawater

Abstract

In this study, two phosphate ceramic coatings (AP‐Al and AP‐Al/Cu) were fabricated via slurry spraying and stepwise high‐temperature curing. The microstructure and phase composition were analyzed by SEM and XRD, while the antibacterial activity and biocorrosion resistance against Pseudomonas aeruginosa in 2216E culture medium were systematically investigated. After curing, the surface compounds of AP‐Al/Cu include AlPO4, Mg2P2O7, Al, Cu, and Cu2O. The addition of copper alleviated high‑temperature curing effects, reduced microporosity, and enhanced local corrosion resistance. After 72 h of co‐culture with P. aeruginosa, AP‐Al/Cu coating exhibited an antibacterial rate exceeding 90%. This improvement is attributed to copper‑induced accumulation of intracellular reactive oxygen species (ROS), leading to bacterial oxidative stress. However, Cu and Cu2O hindered the formation of the Al‐rich protective film and reduced the antimicrobial corrosion resistance. This work demonstrates that Cu incorporation improves both the antibacterial efficiency and local corrosion resistance of the coating, but reduces its electrochemical barrier performance, providing a feasible modification strategy for antibacterial phosphate ceramic coatings.