Hybrid epoxy-SiO2/GO nanosheets anti-corrosive coating for aeronautic aluminum Al6061-T5

Abstract The mechanical and anti-corrosive evaluation of a hybrid epoxy resin–SiO 2 and graphene oxide (GO) are presented. Three composite materials were prepared with 0%, 0.1 wt% and 0.5 wt% GO concentrations. The hybrid material was prepared by the sol-gel process incorporating the silica particles in situ within the epoxy resin (ER) matrix and previously that ER was functionalized with carboxyl groups using abietic acid and labeled as functionalized epoxy resin. The deposition of the three hybrids in aluminum 6061 substrates was made by blade coating, measuring wet and dry film thickness. The study of mechanical properties involved adhesion, pencil scratch hardness, and abrasion test methods where the incorporation of 0.5 wt% of GO improved the mechanical properties considerably. The anti-corrosive properties of the coatings were evaluated through electrochemical impedance spectroscopy and accelerated corrosion using a salt spray chamber showing that GO forms an anti-corrosive barrier increasing the operation life of the coatings in corrosive environments. Anti-ice properties were related to the contact angle measurement from which the GO concentrations showed more hydrophobic behavior. All the tests were carried out according to ASTM standards. The incorporation of 0.5% of GO showed a significant improvement in the mechanical and anti-corrosive results, improving corrosion resistance up to 500 h. The abrasion tests had an increase in 35%, its hardness up to 9H, and the wear index improved by 29.14% compared with composites with 0.1 wt% of GO and without GO. The HREF1 and HREF5 materials do present an increase in the contact angle thanks to the incorporation of graphene oxide. The results of electrochemical impedance spectroscopy and the impedance curves show a better behavior for the HREF5 composite due to the difference in resistance over time.