Preparation Of Graphene/Fe₃O₄ Composites And Their Application In Waterborne Metal Anticorrosive Coatings

Waterborne metal anticorrosive coatings with water as dispersing medium was green and environmentally friendly and in accordance with the strategy of constant development of our country.Nevertheless,the problems of easy formation of holes in the curing process,poor water resistance and poor barrier shielding of corrosive media such as water and oxygen seriously restrict its development.Graphene is suitable for metal anticorrosive coatings due to its excellent mechanical,electrical,chemical stability and barrier properties.It can be used as functional filler to increase its anticorrosive properties.However,due to its surface defects and dispersion problems in waterborne metal anticorrosive coatings,the addition of graphene to waterborne metal anticorrosive coatings can not provide a good protection for metals.Doping Fe₃O₄ into graphene could not only fill the defect of graphene surface and reduce its accumulation problem,but also improve its dispersion in waterborne anticorrosive paint.Therefore,this paper studies mainly focused on preparation of Fe₃O₄nanoparticles,preparating graphene/iron tetroxide?rGO/Fe₃O₄?composites by adding Fe₃O₄ nanoparticles in the reduction process of graphene oxide to graphene,mixing rGO/Fe₃O₄ composites with waterborne paint and studying the anticorrosive property of the obtained modified-paint.The following studies have been carried out:?1?The effects of the ratio of Fe?acac?₃ to PVP,stirring time,reaction time and reaction temperature on the morphology and particle size of Fe₃O₄ nanoparticles prepared by solvothermal method were investigated with single factor method.It was found that the spherical porous Fe₃O₄ nanoparticles with size about 70 nm could be obtained when the ratio of Fe?acac?₃/PVP was 1:2,the stirring time was 5 h,the reaction time was 28 h,and the reaction temperature was 180?.The particle size of Fe₃O₄ was200 nm prepared by using FeCl₃ as iron salt,and showed good dispersion,no agglomeration in a large range,better crystallinity and higher yield.?2?Compared with GO,no oxygen-containing functional groups are found in rGO and the thermal stability of rGO is improved greatly.However,rGO sheets stacked and the defects and porous structure appeared on the rGO surface.However,there is a porous structure on the surface,a lack of filling,and the lamellar accumulation is serious.After introducing Fe₃O₄ nanoparticles with different quality,the stacking phenomenon of the composites was weakened to some extent,the surface defects were filled,and the thermal stability of the composites was improved compared with rGO.?3?The modified waterborne paint was obtained by adding the rGO/Fe₃O₄composite as filler to the waterborne paint.The coatings prepared separately under the same addition amount of different addition components and the different addition amount of the same component.By testing and analyzing the macro-,micro-photograph,basic mechanics,contact angle change,acid-,alkali-,salt-resistance,electrochemical impedance and Tafel polarization curve of coating specimens of modified waterborne paint,it was found that adding rGO/Fe₃O₄ composite material could improve the anticorrosion performance of waterborne paint,and the optimum ratio of rGO to Fe₃O₄is 4:1,the optimum dosage is 1%.In addition,based on the research results of the anticorrosion performance of modified waterborne paint,the possible anticorrosion mechanism of rGO/Fe₃O₄ composites was speculated.