EFFECT OF THE ADDITION OF CERIUM NITRATE AND THE AGING TIME DURING THE SYNTHESIS OF HYBRID TEOS-GPTMS SOL-GEL COATINGS ON THE AA2050-T8 ALUMINIUM ALLOY

Abstract

In the present work, the effect of the addition of the corrosion inhibitor cerium nitrate (Ce(NO3)3·6H2O) and the aging time were evaluated during the synthesis of hybrid sol-gel coatings applied on the AA2050-T8 aluminium alloy. Sols were prepared from a mixture of the precursors tetraethylorthosilicate (TEOS) and glycidoxypropyltriethoxysilane (GPTMS) in a molar ratio TEOS:GPTMS of 3:1, using acetic acid and ethanol as catalyst and solvent respectively. The hydrolysis and condensation process of the hybrid sols was monitored by Fourier Transform Infrared (FTIR) Spectroscopy and rheological tests, whereas sol-gel coatings were characterized using attenuated total reflectance infrared spectroscopy (FTIR-ATR), scanning electron microscopy (SEM), contact angle measurements, and scratch tests. The experimental results showed that the physicochemical characteristics of the hybrid sol-gel coatings obtained were influenced by both the aging time and the addition of the corrosion inhibitor. In this regard, an increase of the aging time resulted in uniform coatings with an adequate adhesion and greater hydrophobic features. On the other hand, the effect of the addition of cerium nitrate in the gelation process was more significant, producing coatings with superior physicochemical features, even for short aging times.