The effect of the organosilane content on the barrier features of sol-gel anticorrosive coatings applied on carbon steel

Abstract

The main objective of this work was to determinate the influence of the molar ratio of two compounds on the structure of the molecular net synthesized by sol-gel technology for the protection corrosion coating on carbon steel. Three different molar ratio were use to prepared the organic–inorganic hybrid materials by hydrolysis and condensation of (3-glycidyloxypropyl)trimethoxysilane (GPTMS) and tetraethylorthosilane (TEOS) in an ethanol/water solution. The behavior of the three different syntheses was evaluated by chemical, physical, and electrochemical methods. The evolution of the synthesis was determinate by FT-IR and viscosity until the optimal moment prior to apply the sol to the metallic substrate. Chemical cross-linking of xerogel was determined by solid state of 29Si-NMR and the behavior on thermal stability is given by TGA analysis. Samples of carbon steel were coated by the synthesis and the coatings were characterized using scanning electrochemical microscopy (SEM) finding considerably differences between the three coatings. Potentiodynamic polarization and impedance measurements were carried out to study the effect of the corrosion resistance of the synthesis in 10 mM NaCl solution.