Preparation of a (3-Mercaptopropyl)triethoxylsilane Film on Copper and Its Corrosion Protective Performance

Abstract

： (3-Mercaptopropyl)triethoxysilane (MPTES) was hydrolyzed in acid or basic ethanol-water solution. Fourier transform infrared (FTIR) spectroscopy was used to characterize the structures of MPTES solutions and MPTES films that formed on copper. The corrosion protective performance of the MPTES films was evaluated by polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that MPTES was hydrolyzed to a certain extent with the formation of Si-OH groups in an acid silane solution and the degree of hydrolysis increased during the aging process of the solution at room temperature. However, a small amount of MPTES was hydrolyzed in the basic silane solution and a large number of SiOCH2CH3 groups were found in it. More Si -O -Si bonds were formed in the film obtained from the acid silane solution compared to the film formed in the basic silane solution. The polarization curves showed that the MPTES films could decrease the corrosion current density of the copper electrodes; the protection efficiencies of the films were 90.3% (for the acid film) and 79.2% (for the basic film). EIS plots indicated that the basic film lost its protective capability after 24 h of immersion in 3.5% (w) NaCl solution while the acid film showed increasing impedance.