Phosphonic acid/silica-based films: A potential treatment for corrosion protection

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.

► Silica/phosphonic acid films were developed for corrosion protection of AA2024-T3.
► Coating properties depend on phosphonic acid concentration, time and temperature of hydrolysis.
► Improved barrier properties were achieved by the addition of silica nanoparticles.