Organosilane-functionalized graphene oxide-epoxy nanocomposite coating: corrosion performance and self-healing properties

In this study, decorated GO nanosheets with 3-glycidyloxypropyl trimethoxysilane (GPTMS) evaluated with Fourier Transformation Infrared Spectroscopy (FT-IR), x-ray diffraction (XRD), Thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDAX). The corrosion performance and of self-healing effect of the nanocomposite coating were examined by electrochemical techniques, Salt Spray, Contact Angle and Scratch test. Corrosion resistance was improved by increasing the percentage of GO from 0.1 to 0.2 wt% for both cases without and with silane agent. Higher impedance resistance (1.12 x 10(10) omega.cm(2)) was obtained for the functionalized one (EPFG) in the early days of immersion. The results of electrochemical and salt spray tests of EPFG nanocomposite coatings were compared epoxy (EP) coatings during various immersion times in 3.5 wt% NaCl solution with and without scratches.Based on our results, after 99 days of immersion, the impedance resistance for EP coating decreased about five orders compared to the EPFG composite coating. The self-healing performance of hydrophobic nanofillers in the matrix of epoxy coating (EPFG) is considered as the reason for increasing resistance after 63 days. The time of reaching corrosive solution to the surface of the steel for the EPFG nanocomposite increased up to 78 days. At all immersion times of the scratched samples, the highest impedance of EPFG composite samples was observed and increasing the impedance of EPFG after 12 days of immersion is related to the formation of a protective film in the metal substrate-coating interface leads to the passive and protective behaviors.

Automated summary

This study evaluated decorated GO nanosheets with various analysis methods and found that increasing graphene oxide content can improve the corrosion resistance of the coating. The functionalized composite coating showed higher impedance resistance in the early stages of immersion. The self-healing performance of hydrophobic nanofillers in the epoxy coating can enhance the corrosion resistance.