Corrosion resistance of magnesium alloy ZK10 coated with hybrid organic-inorganic film including containers

摘要

The main object of this study is the fabrication, characterization and application of corrosion protective coatings to magnesium alloy ZK10. Hybrid organic-inorganic coatings were synthesized using Organic Modified Silicates together with resins based on bisphenol A diglycidyl ether. Cerium molybdate containers loaded with corrosion inhibitor 2-mercaptobenzothiazole were incorporated into the coatings in order to improve their anticorrosion properties. The coatings were investigated for their anticorrosion and nanomechanical properties The morphology of the coatings was examined by Scanning Electron Microscopy.The composition and structure were investigated by FourierTransform Infrared Spectroscopy and Energy Dispersive X-Ray Analysis. The mechanical integrity of the coatings was studied through nanoindentation and nanoscratch techniques. Scanning Probe Microscope imaging of the coatings revealed that the addition of nanocontainers creates surface incongruity; however, the hardness to modulus ratio revealed significant strengthening of the coating with increase of nanocontainers. Studies on their corrosion behaviour in 0.5 M sodium chloride solutions at room temperature were made using electrochemical impedance spectroscopy, cyclic potentiodynamic polarization and open circuit potential. Artificial defects were formatted on the surface of the films in order possible self-healing effects to be evaluated. The results showed that the coated magnesium alloys exhibited only capacitive response after exposure to corrosive environment for 5 months. This behaviour denotes that the coatings have enhanced barrier properties and act as an insulator. Finally, the scratched coatings revealed a partial recovery due to the increase of charge transfer resistance as the immersion time elapsed. In conclusion, the incorporation of nanocontainers loaded with corrosion inhibitor into the epoxy coatings improved the corrosion protective properties of the films. Furthermore, the artificial defected coatings including nanocontainers presented partial recovery suggesting self-healing effect.