Hybrid sol-gel coatings containing clay nanoparticles for corrosion protection of mild steel

IANINA SANTANA; WIDO H. SCHREINER; ANDRÉS PEPE; SERGIO PELLICE; CERE, SILVIA MARCELA

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2016 vol. 203 p. 396 - 403

0013-4686

The development of a new environment-friendly anticorrosive coating for mild steel substrateis afforded in this work. The combined use of cerium, as a self-healing agent, and claynanoparticles, as improvers of the barrier properties, was considered to the development ofnew anticorrosive sol-gel coatings. Nanostructured hybrid films were synthesized by the sol?gel route from tetraethoxysilane (TEOS) and 3-glicidoxipropyl-trimetoxisilano (GPTMS)using laminar nanoclays (Laponite Na+0.7[Si8Mg5.5Li0.3H4O24]-0.7) to improve mechanical andbarrier properties, and Ce(NO3)3?6H2O as a supplier of Ce(III) to provide an inhibiting effectin the event of coating failure. Carbon steel plates, AISI 1010, were used as substrates. Priorto the application of the coating, samples were treated with a phosphoric acid 2 % v/v in orderto improve coating adherence.In order to evaluate cerium effect, electrochemical behaviour of films containing Laponite andcerium salts (TGL-Ce) were compared with films containing only Laponite (TGL) by meansof potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS)measurements using a 0.35 wt% NaCl solution. Microstructural characterization and surfaceanalysis of substrates and sol-gel coatings were performed by optical microscopy and by XPStechniques. The use of nanoclays allowed to achieve a significant improvement of theanticorrosive behaviour of the cerium doped coating at the same time that enhances thephysical integrity of the coatings under immersion tests.