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

IANINA, SANTANA; ANDRÉS, PEPE; SERGIO, PELLICE; SILVIA, CERÉ

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2016

0013-4686

The development of a new environment-friendly anticorrosive coating for mild steel substrate is affordedin this work. The combined use of cerium, as a self-healing agent, and clay nanoparticles, as improvers ofthe barrier properties, was considered to the development of new anticorrosive sol-gel coatings.Nanostructured hybridfilms 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 and barrier properties, and Ce(NO3)36H2O as a supplier ofCe(III) to provide an inhibiting effect in the event of coating failure. Carbon steel plates, AISI 1010, wereused as substrates. Prior to the application of the coating, samples were treated with a phosphoric acid 2%v/v in order to improve coating adherence.In order to evaluate cerium effect, electrochemical behaviour offilms containing Laponite and ceriumsalts (TGL-Ce) were compared withfilms containing only Laponite (TGL) by means of potentiodynamicpolarization tests and electrochemical impedance spectroscopy (EIS) measurements using a 0.35 wt%NaCl solution. Microstructural characterization and surface analysis of substrates and sol-gel coatingswere performed by optical microscopy and by XPS techniques. The use of nanoclays allowed to achieve asignificant improvement of the anticorrosive behaviour of the cerium doped coating at the same timethat enhances the physical integrity of the coatings under immersion tests.