Hydrolysis time influence in obtaining hybrid film with addition of cerium ions for protecting galvanized steels

Abstract

The hybrid films act as a barrier layer between the substrate and the environment. This kind of coating reduces the electrolyte permeability, decreasing the corrosion rate of the substrate. However, many variables influenced the corrosion resistance of hybrid coating. The main factors that influence the thickness of the films are: temperature, curing time, the concentration alcooxide precursors on the bath, the pH of the hydrolysis and the hydrolysis time. In this study, the galvanized steel was coated with and hybrid film obtained from precursors consisting of a sol alcooxide 3-(trimetoxisililpropil) methacrylate (TMSPMA) and tetraethoxysilane (TEOS) with cerium nitrate addition [0,01 M]. The hydrolysis time was varied in four levels of (1, 3, 24 and 48 hours). The characterization of the films was performed by SEM, profilometry, contact angle determination, polarization and electrochemical impedance spectroscopy measurements. Results showed that the hydrolysis time presented influence on the hybrid film properties and consequently on the protection.

Keywords

• hybrid film
• hydrolysis time
• electrochemical impedance