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Synthesis and characterization of anticorrosive coatings of SiO<inf>2</inf> -TiO<inf>2</inf> - ZrO<inf>2</inf> obtained from sol-gel suspensions

Abstract:

The work presented is concerned with the synthesis and characterization ofSiO2-TiO2-ZrO2 stable soles synthesized via sol-gel chemistry. The ternary system were formed in concentrations Si/Ti/Zr: 10/70/20 and Si/Ti/Zr: 10/20/70 using as precursors tetraethyl orthosilicate Si (OC2H5)4, titanium tetrabutoxide Ti(OBu)4 and zirconium tetrabutoxide Zr (OC3H7)4, ethanol (EtOH) and water as solvents, and as complexing 2,4-pentanedione. Characterization of the product was carried out by means of Fourier transform infrared (FT-IR).To investigate the influence of the titanium precursor concentration and determined functional groups presented in the resultant composites. Techniques of Electrochemical Impedance Spectroscopy (EIS) and Tafel curves have been applied with the aim to identify the possibleinfluence of the coatings on the anticorrosive behavior of the steel substrates AISI/SAE 304 in a solution of Hydrocloric Acid-HCl to a concentration of 3%. In particular, we found that for high concentrations of titanium, and low of zirconium, it catalyzes the condensation of silanols. This warrants an adequate mixture of the cations and excludes phase separation in the system. The obtained composites showed that the values of the electrochemical parameters changed substantially with the number of layers deposited on the substrate. Additionally, analysis with complementary techniques to evaluate the micro-hardness of these anticorrosive coatings, have showed that these present variations in their values depending on the concentration and the number of layers applied to the substrate. © 2014 The Authors. Published by ESG.