Corrosion protective properties of nanostructured sol–gel hybrid coatings to AA2024-T3

The work aims at investigating the corrosion behavior of AA2024-T3 substrates pretreated with sol–gel derived hybrid coatings. The hybrid sols were prepared by copolymerization of 3-Glycidoxypropyltrimethoxysilane (GPTMS), tetraethylortosilicate (TEOS) and tetra-n-propoxyzirconium (TPOZ). Coatings with Zr/Si atomic ratios of 1:9 and 1:4 were also prepared. During the synthesis process, there is formation of ZrO2 nanoparticles, which content depends on the temperature and time of the TPOZ hydrolysis/condensation reactions. The results show that the ZrO2 nanoparticles have diameters ranging between 40 and 200 nm. These particles are amorphous and they improve the corrosion protection of the sol–gel coatings. The presence of ZrO2 nanoparticles seems to have a pore blocking effect in the coatings with higher content of particles.