Correlation between electrophoretic clearcoats properties and electrochemical characteristics of noble substrates

The use of transparent organic coatings as protection for noble metal layers has a wide application especially in the costume jewellery and glass frames industry. The role of a clearcoat is to protect the noble substrate from scratches, tarnishing, and changes in gloss due to the interaction with the environment and human body. In this study electrodeposited organic coatings have been considered for this purpose. The application of clearcoats by electrophoresis usually assures a good adhesion to the substrate and the formation of a compact and protective layer. Electrophoresis has been developed especially under cathodic deposition and was mainly optimized for corrosion protection of active metals, but in this work both anodic and cathodic e-coats have been applied and analyzed. Since the substrates were noble metals, the surface could show a different reactivity during the application of the deposition voltage. The relationship between electrochemical behaviour of the substrate and the final properties of the clear coatings was investigated with electrochemical tests such as polarization curves, and electrochemical impedance spectroscopy. The correlation between deposition parameters and coatings properties as thickness and presence of defects was discussed according to the electrochemical results.

► Study of the correlation between metal substrates and clearcoats properties.
► Application of cataphoretic and anaphoretic clearcoats process on noble metals.
► Electrochemical study of barrier properties of clearcoats.