Fabrication Of Organosilane-based Hybrid Functional Coatings On Metal Surface

The traditional anticorrosion technology is chromate passivation technology,but the high toxicity and carcinogenicity of hexavalent chromium make its use limited seriously.In recent years,studies have found that the use of silane coupling agents can firmly adhere to the metal surface through the chemical bond of Si-O-metal,and the silanes can form a three-dimensional network and dense protective film through mutual cross-linking.So,silanization treatment is an effective,green and pollution-free metal surface treatment technology.However,single silane film has the defects of low mechanical strength and generation of micro-cracks,which makes it lack of long-term corrosion resistance.Therefore,we need to adopt some measures to improve the corrosion resistance of the silane film.（1）Two-dimensional MXene（Ti₃C₂）sheets have been hybridized into theγ-glycidoxypropyltrimethoxysilane（γ-GPS）film on 2024 aluminum alloy surface to improve the anticorrosion property.Ti₃C₂ hybridization greatly enhanced the thickness and compactness of the silane film,producing uniform and dense films with fewer defects.The composite films also showed excellent adhesion to the substrate through Si-O-Al chemical bonding.The films inhibited both anode and cathode corrosions by reducing the corrosion current density as well as the diffusion rate of corrosion solution to metal surface.The neutral salt spray tests showed that the corrosion resistance of the Ti₃C₂-hybridized silane film was better than that of the film obtained by traditional chromate treatment.Moreover,the composite films exhibited excellent antibacterial property by having Ti₃C₂ in the film for killing bacteria.The study develops a simple and effective strategy to improve the anticorrosion property of the silane film as well as to introduce antimicrobial ability,which is highly promising for practical applications in the industrial,medical and domestic fields.（2）Another study fabricated a multifunctional silane-based composite surface coating with self-cleaning,anticorrosive and antimicrobial abilities on metal surface.The surface coating is designed to have a“Sandwich”structure that contains a chemically etched surface at the bottom,a Si O₂-hybridized silane layer in the middle and a Ti₃C₂-hybridized silane layer on the top.The chemical etching produces a rough surface that helps to produce superhydrophobicity.The silane molecules are crosslinked to form a film of low surface energy,which not only contributes to surface superhydrophobicity but also plays dominant roles in corrosion resistance.The Si O₂ nanoparticles and Ti₃C₂ nanosheets are hybridized in the film to enhance compactness,mechanical strength and wearing resistance of the film,resulting in a surface coating with excellent anticorrosion efficiency.Ti₃C₂ can also introduce antimicrobial ability to the surface coating.The study develops an effective strategy to construct multifunctional composite surface coatings,which is not only suitable for modification of clinical and biomedical devices for anticorrosive and antibacterial purposes,but also can be used to modify the surface of daily-use facilities to facilitate their daily maintenance and cleaning.