Effects of Self-assembled Film Microstructure on Corrosion Resistance of Aluminum Alloy Surface

In order to study the influence of the microstructure of self-assembled films with different functional groups on the corrosion resistance of aluminum alloy. Lauric acid, bis(gamma-triethoxysilylpropyl) tetrasulfide (BTESPT) and ammonium sebacate self-assembled film were prepared on the surface of Al by self-assembled film technology. Scanning electron microscope, X-ray energy spectrometer, contact angle analyzer, and infrared spectrometer were used to characterize the films, the electrochemical and corrosion protection performance of the films were discussed respectively. The results shows that the three self-assembled films all have been successfully prepared, moreover, the BTESPT film structure was densest among the films. The EIS and Tafel plot shows that the impedance values of the three layers have reached 3. 3x10(7), 1. 1x10(15), 6. 8x10(7) Omega center dot cm(2), the corrosion current density reached 4. 5x10(-7), 5. 6x10(-8), 9. 6x10(-8) A/cm(2). Corrosion mechanism of the film is discussed by the fitting circuit diagram. Salt spray test results shows that the corrosion point appeared on the 16th day of the BTESPT film. A result is obtained that the BTESPT film has the best corrosion resistance due to its dense film structure.