Corrosion protection of carbon steel by silica-based hybrid coatings containing cerium salts: Effect of silica nanoparticle content

• Published in: Surface & coatings technology 2015-03, Vol.265, p.106-116
• Main Authors: Santana, Ianina, Pepe, Andrés, Jimenez-Pique, Emilio, Pellice, Sergio, Milošev, Ingrid, Ceré, Silvia
• Format: Article
• Language: English
• Subjects: Acer al carboni; aluminum-alloys; aqueous systems; behavior; Carbon steel; Carbon steels; Cerium; Coatings; conversion coatings; Corrosion; Electrochemical impedance spectroscopy; Enginyeria dels materials; galvanized steel; Hybrid coating; Nanoparticles; Nanopartícules; Nanostructure; phase-stability; Rare earth metals; rare-earth salts; Revestiments protectors; Scanning electron microscopy; silane films; Silica nanoparticles; Silicon dioxide; sol-gel coatings; Àrees temàtiques de la UPC
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2015.01.050

One strategy for minimising corrosive attack on carbon steel involves the application of hybrid coatings rich in rare earths, on the basis of their low toxicity and environmental sustainability. Tetraethoxysilane (TEOS) and 3-glycidoxypropyl-trimethoxysilane (GPTMS) were each used here as precursors, together with various quantities of colloidal silica suspension, to improve barrier properties of the coatings. Ce(NO3)3·6H2O was added as a source of Ce(III) for further inhibition of corrosion. The corrosion resistance of each kind of sample was evaluated using potentiodynamic polarisation measurements and electrochemical impedance spectroscopy (EIS) in 0.35wt.% NaCl solution. The electrochemical behaviour at various immersion times was modelled by equivalent circuits to demonstrate the effect of silica nanoparticle loading on corrosion. Additional testing was performed under harsh conditions of salt spray chamber. The microstructure and composition of sol–gel coatings were characterised by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS), focused-ion beam SEM/EDS analysis, X-ray photoelectron spectroscopy and confocal microscopy. •Hybrid coatings containing silica nanoparticles and cerium ions were applied on carbon steel.•At higher content of nanoparticles, both thickness and barrier effect enhance.•Bi layer coatings with silica nanoparticles and cerium ions offer the best combination for protection.