Abstract: Bis-[triethoxysilylpropyl] tetrasulfide silane films were self-assembled on surface of 2A12-T6 aluminum alloy for corrosion protection. The structure of the formed silane films was investigated by using Fourier transform infra-red (FTIR) spectroscopy, and the corrosion performance of the film was evaluated by electrochemical potentiodynamic polarization tests in 3.5% NaCl solution. Compared to the untreated case, both the cathodic and anodic reactions of Al 2A12-T6 treated with the silane films are inhibited obviously. For the film on the surface of Al 2A12-T6 aged at room temperature the corrosion current density is reduced by more than 1 order of magnitude, which is due to the hydrogen bonding between silane molecules and surface of 2A12-T6. For the film on the surface of Al 2A12-T6 cured at temperature of 120 ℃ for 40 min the silane molecules are cross linked through SiOSi, which is closely linked to Al 2A12-T6 surface through formation of SiOAl. The corrosion current density is reduced by more than 2 orders of magnitude. There exist more hydrogen bonded hydroxy groups in the cured film dipped for 10 min in the prepared silane solution than that dipped for 2 s to 1 min.

Key words: Aluminium alloy, Bis-[triethoxysilylpropyl]tetrasulfide, Fourier transform infra-red, Film, Corrosion