Dual-Function Hybrid Coatings Based on Polytetrafluoroethylene and Cu₂O for Anti-Biocorrosion and Anti-Wear Applications

Corrosion and wear issues of motion components exposed to water-based corrosion mediums, e.g., naval vessels and oil extraction equipment, pose challenges for the lifespan and reliability of the motion systems. In this work, epoxy-based coatings modified with polytetrafluoroethylene (PTFE) and cuprous oxide (Cu₂O) nanoparticles were prepared. The anti-corrosion performance of the coatings was comparatively investigated by electrical impedance spectroscopy and Tafel tests in sterile and sulphate-reducing bacteria (SRB) mediums. Moreover, the tribological behaviors of the coatings were examined under water lubrication conditions. Our results demonstrate that the epoxy coatings lower significantly the corrosion current density i_corr and the charge transfer resistance of the electrical double layer R_ct of the carbon steel substrate. Interestingly, the hybrid coatings filled with both PTFE and Cu₂O exhibit excellent anti-corrosion and anti-wear performance. After being immersed in the SRB medium for 18 days, the i_corr of the pure EP coating and hybrid coatings are 1.10 × 10⁻⁷ A_mp/cm² and 0.3 × 10⁻⁷ A_mp/cm², and the R_ct values are 1.04 × 10³ Ω·cm² and 3.87 × 10³ Ω·cm², respectively. A solid tribofilm forms on the stainless steel counterface sliding against the hybrid coating, which is surmised to be essential for the low friction coefficients and wear. The present work paves a route for formulating the dual-function coatings of anti-biocorrosion and anti-wear.