Assessment of ZnO nanoparticles as anticorrosive pigment in hybrid sol–gel films

Abstract

Abstract The present work is focused on the study of sol–gel hybrid films doped with 0.5% (w/w) ZnO nanoparticles and applied on commercial tinplate. The sol–gel matrix was prepared from two precursors: tetra- n -propoxyzirconium (TPOZ) and 3-glycidoxypropyltrimethoxysilane (GPTMS). The incorporation of particles was carried out by two procedures: as received or after functionalization with GPTMS precursor. The interfacial chemistry of the ZnO was studied by the evaluation of the particle size (hydrodynamic diameter) and the zeta potential. The obtained results indicated that particle size was not affected by the chemical treatment. However the zeta potential changed from positive values (+19 mV) for as received ZnO, to negative ones (−44 mV) when they were treated, which corroborated the effectiveness of the functionalization process. The anticorrosive properties of the sol–gel films were evaluated by Electrochemical Impedance Spectroscopy (EIS) technique. The results showed a clear effect of ZnO nanoparticles on the barrier properties of the film, which was more evident when those had been functionalized. An additional inhibiting action was proposed, based on the higher impedance values observed for doped samples.