The effects of TiO2 addition on the anticorrosion performance of ECTFE coating under lighting

In this study, TiO 2 particles were dispersed into ethylene-chlorotrifluoroethylene copolymers (ECTFE), and TiO 2 /ECTFE composite coating was prepared with the TiO 2 /ECTFE mixture via electrostatic spraying and low temperature thermal processing. The prepared coating was soaked in 3.5 wt% NaCl solution under lighting or dark for anticorrosion performance study. The microstructure of the treated coating was characterized with XRD , Raman, FT-IR and SEM. The results indicate that the low frequency impedance (|Z| 0.01 Hz ) of the TiO 2 /ECTFE coating maintained above the 10 9 orders of magnitude after 90-day soaking. It is evident that the addition of TiO 2 enhances the protective performance of the coating on steel, while simultaneously compromising its own integrity. With increasing soaking time, C-H groups in ECTFE coating would be exposed gradually and lighting would speed this process, making the surface roughness of coating reduced. This is because halogens in the polymer chain of ECTFE would be stretched gradually. TiO 2 would also change the bond length of C-H groups and make the C-H groups oxidized under lighting. The strengthening effect of TiO 2 can be ascribed to the filler and barrier effects of TiO 2 particles together with the prior consumption of dissolved oxygen by photo-generated electrons. However, the fast degradation of TiO 2 /ECTFE coating under lighting is the result of local agglomeration of TiO 2 particles, and oxidation of the C-H groups by photo-generated holes.