Study on corrosion resistance of the BTESPT silane cooperating with rare earth cerium on the surface of aluminum-tube

Bis-[3-(triethoxysilyl)propyl]tetrasulfide (BTESPT) silane-rare earth cerium composite coatings on aluminum-tube were prepared at 60 °C by immersion method. The performance of composite coatings to protect the aluminum-tube against corrosion was investigated with potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and salt spray test (SST). The results of potentiodynamic polarization curves and EIS indicated that the self-corrosion current decreased by two orders of magnitude and the impedance values increased to 20 kΩ/cm2; the result of salt spray test showed that the anti-corrosion time increased by three times, which indicated that the corrosion resistant capability of the composite coatings was improved significantly. The scanning electron microscopy (SEM) photograph showed that the conversion coating was uniform and dense. The energy dispersive spectrometer (EDS) was used to analyse coating composition, which was mainly S, O, Si, Al and Ce. The formation and corrosion mechanism of the composite coating were also studied.