Abstract
In this work, layers of a sol-gel hybrid matrix doped with metal oxide nanoparticles (TiO2 NPs) have been deposited on flat samples of AA6061-T6 aluminum alloy using the dip-coating technique, with the aim of obtaining coatings with better anti-corrosive and hydrophobic properties. Two different organic modified silica alkoxides, namely 3-(glycidyloxypropyl)trimethoxysilane (GPTMS) and methyltriethoxysilane (MTEOS), have been used for an adequate entrapment of the metal oxide nanoparticles. In addition, a fluorinated metal-alkoxide precursor has also been added to the hybrid matrix in order to improve the hydrophobic behavior. The experimental results corroborate that the presence of these TiO2 NPs play an important role in the development of the sol-gel hybrid coatings. The water contact angle (WCA) measurements, as well as pencil hardness tests indicate that TiO2 NPs make a considerable increase in the resultant hydrophobicity possible, with better mechanical properties of the coatings. The coating thickness has been measured by cross-section scanning electron microscopy (SEM). In addition, a glow discharge optical emission spectroscopy (GD-OES) analysis has been carried out in order to corroborate the adequate entrapment of the TiO2 NPs into the sol-gel coatings. Finally, potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) have been performed in order to evaluate the corrosion resistance of the coatings. All the results provide insights into the efficacy of the developed sol-gel hybrid coatings for anticorrosive purposes with good mechanical properties.
Highlights
IntroductionAfter steel and cast irons, are the group of metallic materials most widely used in industry
Aluminum and its alloys, after steel and cast irons, are the group of metallic materials most widely used in industry
The incorporation of precursor based on fluorinated chains (PFAS) into the previous increase in the wettability from 98.51 ± 2.32° up to 120.76 ± 2.17°, which corresponds to an hybrid matrix composed of TiO2 NPs and a further thermal treatment produced an increase in the improvement of 22.5% in the hydrophobic property of the sol-gel coatings
Summary
After steel and cast irons, are the group of metallic materials most widely used in industry. In order to overcome this, the new trends are based on the use of sol-gel coatings modified with inorganic nanoparticles with the aim of obtaining a better mechanical resistance In this sense, most of the research lines are focused on the incorporation of silica nanoparticles for obtaining sol-gel superhydrophobic surfaces with enhancement in the resultant hardness [46,47,48,49]. This work proposes a novel type of sol-gel coating based on the incorporation of inorganic titanium dioxide nanoparticles (TiO2 NPs) into a sol-gel hybrid matrix by using a copolymerization process of two organic modified silica alkoxides precursors, namely methyltriethoxysilane (MTEOS). The combination of the barrier protection effect of silica coating and the improvement in the mechanical properties due to the addition of metal oxide nanoparticles can be used for the design of novel protective coatings against corrosion for industrial applications
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