Study On The Surface Protection Film Of Aluminum Alloy And Its Corrosion Resistance By Layer Self Assembly

Aluminum alloys are widely used in ships,offshore platforms and construction projects due to their excellent physical and mechanical properties.However,the corrosive environment of the ocean makes aluminum alloys vulnerable to corrosion.In order to improve the corrosion resistance of aluminum alloy and expand the range of application of aluminum alloy,it is necessary to surface corrosion resistance of aluminum alloy.In this paper,the surface protective film of aluminum alloy was prepared by layer by layer self-assembly technology.The microstructure and properties of the protective film were studied based on a variety of microscopic testing techniques.The corrosion resistance of the protective film was verified by salt spray corrosion test.The main research:(1)A dense and porous anodic alumina film was prepared on the surface of aluminum alloy by oxalic acid anodizing method.The alumina sol film was prepared by sol-gel method and its sealing treatment was realized.By scanning electron microscopy(SEM),electron spectroscopy elemental analysis(XPS),X ray diffraction(XRD),atomic force microscopy(AFM),and other means to analyze the surface morphology of anodic oxide film and sol gel film structure.The results show that the anodic oxidation method can produce amorphous alumina film on the surface of aluminum substrate,and the film is porous structure,and has excellent shielding effect.The sol gel method can be applied on the surface of alumina film to form a layer of alumina sol,which has excellent sealing effect.(2)layer by layer self-assembly method was used to adsorb poly(acrylic acid)and polyethyleneimine onto the surface of aluminum alloy after sealing treatment,and the improved layer by layer self assembled film was obtained.The micro morphology and electrochemical analysis based on self-assembly of polyelectrolyte multilayer film for composite film thickness and composition is relatively uniform,with a very high density,which can avoid direct contact with the corrosive medium and aluminum alloy.(3)the neutral salt spray test was carried out on aluminum alloy,aluminum alloy oxide film and layer by layer self assembled film.The corrosion resistance of various kinds of films was analyzed by electrochemical and micro test techniques.The results show that the Aluminum Alloy matrix and poor corrosion resistance of anodic oxide film,protective film can enhance the ability to resist chloride ion erosion by sol gel after sealing,polyethyleneimine and polyacrylic acid corrosion resistance layer by layer self assembled film best,after 168 h salt spray corrosion after only a slight surface pitting,the surface structure is not changed,the aluminum matrix effectively protection.