Composite Passivation Technology Based On POSS Modified Graphene Oxide

The hot dip galvanization is a protection method of steel material at the expense of galvanized layer.However,zinc can not spontaneously form a passive film in the atmosphere.Thus,hot dip galvanized steel need to be treated by passivation to ensure the long-term effectiveness of corrosion protection.Because chrome passivation is harmful to the human body and environment,it is imperative to seek effective chromium-free passivation processes.Recently,the anti-corrosion application of graphene material has increased.In this work,aminopropylisobutyl polyhedral oligomeric silsesquioxane modified graphene oxide and octa-aminopropyl polyhedral oligomeric silsesquioxane modified graphene oxide were synthesized by the amidation reaction.Subsequently,modified graphene oxides were applied to a waterborne acrylic acid passivation agent and the hot dip galvanized steel was treated by the passivation agent.The contents of modified graphene oxide were optimized in the passivation agent by evaluating the corrosion resistance of passivation films.And the morphology,chemical composition and corrosion resistance of passivation films were characterized,further,the corrosion resistance mechanism of the composite passivation film was discussed.The stable dispersion of two types of modified graphene oxide in different solvents were improved.Optimized contents of modified graphene oxide in passivation agents were both 0.1 g/L.Surface defects of composite passivation films were less,and porosities both decreased by more than 30%compared with that of the non-additive based passivation film.Moreover,the surface roughness and wettability also decreased to different degrees.The results of electrochemical measurements reveal that the corrosion resistance of aminopropylisobutyl polyhedral oligomeric silsesquioxane modified graphene composite passivation film was better,with a corrosion current density of 17.01 A·cm^-2and a corrosion rate of 0.25 mm/a,which were an order of magnitude lower than that of the based passivation film.The reasons for the corrosion resistance promotion of composite passivation films:modified graphene oxide promote the crosslinking of the organic passivation film,and effectively inhibited the transfer of materials and charge near the base metal in the corrosion system,therefore improving the corrosion protection performance of the composite passivation film.