Performance Of Silane Self-assembled Films On Aluminum Sheet

Silane-based surface treatment on metal surface as a new environment-friendly surface protection technology is a very promising alternative in Anti-corrosion areas for aluminum metal. However, the current study mostly focused on Self-Assembled Monolayers, the film was too thin, and this limited its corrosion resistance.In order to increase the thickness of the film, prepared double layer silane film based on Self-Assembled Monolayers, and then added corrosion inhibitor and nanoparticles in the. film to get a high mechanical strength and self-healing film. In this paper, Silane self-assembled films were prepared by nontoxic, no polluted Bis-l,2-[triethoxysilylpropy]tetrasulfide and y-glycidoxypropyltrimethoxysilane. Cerous nitrate and ceria nanoparticles were added to the film. Studied the preparation of silane films and tested corrosion properties of metals pretreated by them.The progress parameters (hydrolysis time, dipping time, curing temperature, curing time and additive concentration) were determined by Tafel test, and then discussed their influence of the corrosion resistance. The corrosion resistances of the films were studied by Tafel test, Immersion test and dropping corrosion test. The results show that double layer composite silane film which had been added ceria nanoparticles had the best corrosion resistance, its corrosion current was4.25×10-9A, reduced by3orders of magnitude compared with blank sample, its Cu2+corrosion resistance time was18’01"were the shortest among the films. Immersed in3.5%NaCl solution for15days, the film’s had only0.1mg weight loss.FT-IR spectra test showed that, the simple layer silane film contained Si-O-Si bond and Si-O-Al bond. These bonds showed that Silane molecules were therefore reacting with the Al substrate forming an interface with Si-O-Al bonds and simultaneously building up a cross-linked silane film with Si-O-Si bonds. The double layer silane film contained Si-O-Si bond and Si-O-Al bond and epoxy group. Epoxy group showed that GPTMS film was formed on the top. Cerous nitrate and ceria nanoparticles were in the form of physical absorption for silane films.Scanning electron microscope were applied to observe the morphology of the films, the result showed that the aluminum surface was covered with a uniform, dense and concave-convex film. The morphology made the film had some extent hydrophobicity. The morphology of all kinds of film was similar; indicated that a certain amount of additive didn’t change the structure and morphology of the films.