Synthesis by Sol-gel Route and Characterization of Ceria Doped Silica Coatings on Commercial Carbon Steel

Abstract

The use of silane formulations for the pre-treatment of metallic substrates prior to painting or as topcoat has been increasing during the recent years. The proposed formulations are very attractive because they present environmental friendliness, enhance adhesion properties and provide a barrier layer that delays the corrosion processes. One of the most used techniques to synthesized based-SiO 2 coatings is solgel. The preparation of sol-gel coatings with specific chemical functions offers potential advantages over traditional methods as it offers tailoring of their structure, texture and thickness and allows the fabrication of large coatings. The present work investigates the electrochemical behaviour of commercial carbon steel coated with ceria doped SiO 2 by sol-gel process in basic media. To evaluate the influence of temperature on adhesion and protective properties, the coatings were sintered at three different temperatures, 623 K, 723 K and 873 K, for 3 h. The anticorrosion behaviour, of the films has been characterized in an aggressive medium by electrochemical techniques, while structural characteristics and morphology was followed by X-Ray Diffraction, Fourier Transformed Infra-Red and Scanning Electron Microscopy techniques. The results indicated that the thin films act as a protective barrier against exposure to the corrosive medium (3.5 wt-% NaCl solution) and increase the lifetime of the susbtrate.

Corrosion Protection of A36 Steel with SnO2 Nanoparticles Integrated into SiO2 Coatings

“…Tetraethyl orthosilicate 0.35 M (TEOS) was used as the chemical precursor and water and ethanol were used as solvents, while NH 4 OH 0.038 M was added to the solution as a catalyst. The solution was stirred for 12 h to allow hydrolysis and condensation reactions to occur, in accordance with the method of Domínguez-Crespo [32]. Later, the SnO 2 particles were added at 0, 1%, 2.5%, 5%, and 7.5% by volume and the sol was stirred for 30 min in an ultrasonic bath for dispersion.…”