| The aluminum alloy as a light metal,the field of application is also very extensive,the aluminum alloy surface is particularly vulnerable to the formation of oxide film to protect the aluminum alloy,but when the oxide film suffered permanent damage,poor corrosion resistance of aluminum alloy is also revealed.In this paper,a simple,low-cost and green non-polluting method is used to prepare a protective film on the surface of aluminum alloy 6061 to improve its corrosion resistance.Three kinds of corrosion protection film via a variety of different methods were prepared on the surface of the aluminum alloy 6061,respectively.Electrochemical test was conducted in a strong acidic test solution 0.5 M H2SO4+2 ppm HF to investigate their corrosion resistance.In addition,the film on the surface of aluminum alloy and its chemical composition were also analyzed and discussed through various characterization methods.The main findings are as follows:First,a graphene-tin oxide composite film was prepared on aluminium alloy 6061 by self-assembly and hydrothermal methods.The surface morphology of the film was investigated using field-emission scanning electron microscopy?SEM?.The composition and microstructure were investigated using X-ray diffraction?XRD?,raman spectroscopy and X-ray photoelectron spectroscopy?XPS?.The corrosion behaviour of the film was studied using an electrochemical method in a mixed acidic solution of 0.5 M H2SO4 and 2 ppm HF.The resulting protection efficiency was up to 99.727%,illustrating that the film can immensely improve the corrosion of this alloy in a heavily acidic environment.Second,a high-anticorrosion pyrolysis film of chitosan successfully was fabricated on the surface of aluminum alloy 6061.Chitosan is an environmentally friendly multi-carbohydrate material.Because its molecular structure contains a great amount of amino and hydroxyl functional groups,it can obtain the carbon source via pyrolysis.Corrosion behavior of the as-prepared film was studied via Electrochemical Impedance Spectroscopy?EIS?,Tafel polarization curve and equivalent circuit in a mixed acidic solution of 0.5 M H2SO4+2 ppM HF.The surface morphology and composition were characterized by SEM and its affiliated energy dispersive spectrometer,atomic force microscope?AFM?,?XRD?,raman spectrum,fourier transform infrared spectroscopy?FT-IR?and XPS,respectively.The results showed that the as-prepared film on AA 6061 was a nitrogen-doped graphitized carbon film.The corrosion current density of pyrolysis film on AA 6061compared that of bare AA 6061 was down dramatically from 1.247×10-4 A·cm-2 to7.461×10-8 A·cm-2,which exhibited a very high protection inhibition of 99.940%.Third,The polyethyleneimine?PEI?-graphene oxide?GO?-chitosan composite film was successfully prepared on the surface of aluminum alloy 6061 by the self-assembly method.This method mainly utilizes the hydrogen bonding or electrostatic attraction between different materials to realize the compounding of the three materials.The surface morphology of the composite films was investigated by SEM,and the composition and microstructure of the films were investigated by raman spectroscopy and XPS.The corrosion behavior of PEI-GO-chitosan composite film in mixed acid solution of 0.5 M H2SO4+2ppm HF was studied by electrochemical test.The results showed that the protective efficiency of PEI-GO-chitosan composite membrane was as high as 99.985%in the acidic solution,illustrating that PEI-GO-chitosan composite film can effectively improve the corrosion resistance of the aluminum alloy in acidic environment. |
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