Film forming kinetics and reaction mechanism of γ-glycidoxypropyltrimethoxysilane on low carbon steel surfaces

• Published in: Applied surface science 2010-09, Vol.256 (22), p.6787-6794
• Main Authors: Yang, Lixia, Feng, Jun, Zhang, Wenguang, Qu, Jun-e
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Density functional theory, local density approximation; Electron states; Exact sciences and technology; Film forming kinetics; Infrared and Raman spectra; Infrared and raman spectra and scattering; Materials science; Metal; Methods of deposition of films and coatings; film growth and epitaxy; Methods of electronic structure calculations; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Silane films; Structure and morphology; thickness; Theory and models of film growth; γ-Glycidoxypropyltrimethoxysilane
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2010.04.090

The film forming kinetics and reaction mechanism of γ-GPS on low carbon steel surfaces was investigated by FTIR-ATR, AFM, NSS and theoretical calculation method. The results from experimental section indicated that the reaction of γ-GPS on low carbon steel surfaces followed the conventional reaction mechanism, which can be described as reaction (I) (Me (Metal)–OH + HO–Si → Me–O–Si + H 2O) and reaction (II) (Si–OH + Si–OH → Si–O–Si + H 2O). During film forming process, the formation of Si–O–Fe bond (reaction (I)) exhibited oscillatory phenomenon, the condensation degree of silanol monomers (reaction (II)) increased continuously. The metal hydroxyl density had significant influence on the growth mechanisms and corrosion resisting property of γ-GPS films. The results from theoretical calculation section indicated that the patterns of reaction (I) and reaction (II) were similar, involving a nucleophilic attack on the silicon center. The formation of Si–O–Fe bond (reaction (I)) was kinetically and thermodynamically preferred, which had catalytic effect on its condensation with neighboring silanol monomers (reaction (II)). Our DFT calculations were good consistent with the experimental measurements.