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Materials (Basel). 2017 Mar 17;10(3). pii: E306. doi: 10.3390/ma10030306.

Hybrid Coatings Enriched with Tetraethoxysilane for Corrosion Mitigation of Hot-Dip Galvanized Steel in Chloride Contaminated Simulated Concrete Pore Solutions.

Author information

1
LNEC, National Laboratory for Civil Engineering, Av. do Brasil 101, Lisboa 1700-066, Portugal. rita@figueira.pt.
2
"Klaus Müller" NMR Laboratory, Department of Industrial Engineering, University of Trento, Via Sommarive, 9, Trento 38123, Italy. emanuela.callone@unitn.it.
3
Centro de Química, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal. csilva@quimica.uminho.pt.
4
LNEC, National Laboratory for Civil Engineering, Av. do Brasil 101, Lisboa 1700-066, Portugal. epereira@lnec.pt.
5
"Klaus Müller" NMR Laboratory, Department of Industrial Engineering, University of Trento, Via Sommarive, 9, Trento 38123, Italy. sandra.dire@unitn.it.

Abstract

Hybrid sol-gel coatings, named U(X):TEOS, based on ureasilicate matrices (U(X)) enriched with tetraethoxysilane (TEOS), were synthesized. The influence of TEOS addition was studied on both the structure of the hybrid sol-gel films as well as on the electrochemical properties. The effect of TEOS on the structure of the hybrid sol-gel films was investigated by solid state Nuclear Magnetic Resonance. The dielectric properties of the different materials were investigated by electrochemical impedance spectroscopy. The corrosion behavior of the hybrid coatings on HDGS was studied in chloride-contaminated simulated concrete pore solutions (SCPS) by polarization resistance measurements. The roughness of the HDGS coated with hybrids was also characterized by atomic force microscopy. The structural characterization of the hybrid materials proved the effective reaction between Jeffamine® and 3-isocyanate propyltriethoxysilane (ICPTES) and indicated that the addition of TEOS does not seem to affect the organic structure or to increase the degree of condensation of the hybrid materials. Despite the apparent lack of influence on the hybrids architecture, the polarization resistance measurements confirmed that TEOS addition improves the corrosion resistance of the hybrid coatings (U(X):TEOS) in chloride-contaminated SCPS when compared to samples prepared without any TEOS (U(X)). This behavior could be related to the decrease in roughness of the hybrid coatings (due TEOS addition) and to the different metal coating interaction resulting from the increase of the inorganic component in the hybrid matrix.

KEYWORDS:

alkaline environment; chlorides; coatings; corrosion mitigation; hybrids; sol-gel

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