Environmentally friendly sol - gel-based anticorrosive coatings on aluminum alloy 2024

Abstract

Chromate coatings used as corrosion protection technologies for aluminum alloys are environmentally harmful and extremely toxic. This paper presents an investigation on the deposition of environmentally friendly cerium oxide-based anticorrosive coatings on aluminum alloy 2024 substrates by the sol-gel method. The influence of the calcination temperature on both the microstructural characteristics and the electrochemical corrosion performance was tested using scanning electron microscopy, X-ray diffraction, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), before and after, periods of immersion in saline corrosive solutions. The ceramic coatings synthesized at 200, 300 and 400 °C showed very resistive behaviors leading to both an efficient passivation of the alloy surfaces and good corrosion protection. This passivation was maintained for 30 days of immersion in saline solutions, as well as, when aggressive electrochemical polarization experiments (until 2.0 V versus saturated calomel electrode) were used. Very high resistances for the charge transfer (0.14-0.28 GΩ) and very low current density values (5 × 10 -14 -5 × 10 -11 A cm -2 ) were estimated by EIS and potentiodynamic polarization, respectively, for coatings prepared at 200-400 °C. Thus, the coatings prepared in this study by the sol-gel method appear as an efficient treatment for the corrosion protection of aluminum alloys.

Influence of the annealing temperature and metal salt precursor on the structural characteristics and anti-corrosion barrier effect of CeO2 sol–gel protective coatings of carbon steel

“…These films have proven to be an effective barrier against substrate ion diffusion and high temperature inhibition of the oxidation process, even during densification thermal treatments [15]. Several researches have reported the use of the sol-gel method to deposit diverse anticorrosive coatings on carbon steel [16][17][18] and aluminum alloy [19][20][21][22], as well as the deposition of corrosion protection coatings using cerium salts as precursor solutions [23][24][25][26].…”

Structural Characterization and Dielectric Properties of the Effect of Carbon Nanotubes and Silicon on AA2024 Metal Matrix Composites

“…This observation con rms the presence of aluminium as indicated by Giancarlo Richard Salazar-Banda et. al., (2013)[17],Sourabh Biswas et. al., (2017) [18] and M. Senthil Kumar et.…”

structural characterization and dielectric properties of the effect of carbon nanotubes and silicon on AA2024 Metal Matrix Composites

“…This observation con rms the presence of aluminium as indicated by Giancarlo Richard Salazar-Banda et. al., (2013)[17], SourabhBiswaset. al., (2017)[18] and M. Senthil Kumar et.…”