Pre-treatment with hybrid films obtained by the sol-gel from specific alkoxide precursors has been an environmentally friendly alternative, proposed for the corrosion protection of metallic substrates, including galvanized steel. In hybrid films, inorganic compounds contribute to the increase of corrosion resistance and adhesion to the metallic substrate, while organic compounds increase the density, flexibility and functional compatibility with organic systems, such as painting. The addition of corrosion inhibitors or other compounds, to the hybrid films can modify the properties of the barrier layer, improving corrosion resistance. In this study, galvanized steel was pre-treated with a hybrid film obtained from a sol consisting of alkoxide precursors: 3 - (trimetoxisililpropil) methacrylate (TMSPMA) and tetraethoxysilane (TEOS) with the cerium nitrate addition (0.01M). The hybrid films were submitted to different curing processes: air-drying, thermal curing and ultraviolet curing. The obtained systems were characterized according to adhesion, morphology and electrochemical behavior. Besides, the degree of hydrophobicity of the systems was measured by contact angle measurements. For the accelerated corrosion tests in salt spray, the galvanized steel, pre-treated with a hybrid film, was coated with epoxidic painting. The results showed that the system using galvanized steel/hybtrid film/paint, with hybrid films cured by air -drying and ultraviolet radiation, presented the best results for corrosion resistance.
Galvanized steel; hybrid films; epoxy painting; corrosion resistance
