Synergistic Surface Modification of Aluminum by Silane and Corrosion Inhibitor

Bis-[-3-(triethoxysilyl)propyl] tetrasulfide(a kind of silane,abbreviated as BTESPT)and an organic acid ester with long chain alkyl group(inhibitor A throughout)were used to synergistically passivate aluminum.Thus the Al samples were sequentially immersed in the silane(BTESPT)solution and inhibitor A solution,allowing the formation of compact hydropho-bic complex film on the surface of the Al surfaces.The final syn-ergistic passivation film was obtained by drying the hydrophobic complex film at 100℃ for 12 h.The corrosion resistance of the synergistic passivation film was evaluated using hydrogen-evolution test,weight loss test in alkaline solution,salt-fog test,and electrochemical test.The microstructure of the passivation film was examined by means of scanning electron microscopy(SEM),and the film-formation mechanism and the corrosion resistant mechanism of the film were discussed.It was found that the complex passivation film had excellent corrosion resistance.No heavy metals and fluorides were detected in the composite passivation film,meeting the requirements of European ROHS standard.