The protection of aluminum alloy 2024-T3 imparted by (3-glycidyloxypropyl)trimethoxysilane (GPTMS)/vinyltrimetoxysilane (VTMS) sol-gel films and the incorporation of ethylenediamine tetra(methylenephosphonic acid) (EDTPO) into silica matrix has been investigated. The corrosion behavior in chloride solution depends on the GPTMS/VTMS ratio. The protective performance has been improved by achieving a better coverage surface through the addition of EDTPO to sal-gel films. Nevertheless, EDTPO catalyzes the opening of epoxy ring, promoting the hydrophilic character of the silica surface. On the other hand, the incorporation of functionalized silica nanoparticles into silica/EDTPO matrix affords long-term corrosion protection due to the enhancement of barrier properties. (C) 2015 Published by Elsevier Ltd.
Films of tetraethyl orthosilicate (TEOS) and 1,2-diaminoethanetetrakis methylenephosphonic acid (EDTPO) were evaluated as a anticorrosive treatment against corrosion for AA2024-T3 in a 0.05 mol L−1 NaCl solution. The electrochemical behavior was investigated using electrochemical impedance spectroscopy. The chemical composition of the silanization bath and films were analyzed by infrared spectroscopy. The effect of hydrolysis time on sol–gel TEOS/EDTPO was monitored, being obtained the best performance after 72 h of hydrolysis at 25 °C. The optimal concentration of EDTPO within the TEOS matrix was 3.75 × 10−4 mol L−1. Improved barrier properties of these films were achieved by the addition of silica nanoparticles.
Accelerated immersion tests have been carried out in the laboratory to investigate the performance of polyaniline emeraldine salt and polypyrrole composite with carbon black as additives of an epoxy paint coating. The steel panels coated with paint modified with polyaniline emeraldine salt presented the best protection after 720 h of exposure in 3.5% NaCl solution. The results indicated that this conducting polymer might works as both corrosion inhibitor and adhesion promoter. The protective mechanism imparted by conducting polymers is also discussed.