Study On The Preparation And Corrosion Properties Of Gnps/Polymer Composite Coatings

With the development of marine resources prospecting,the consumption of steel in marine is also on the rise year by year.Steel corrosion question in marine environment has been concerned by the international community.Among various kinds of anti-corrosion technologies,coating anti-corrosion material has been widely used because of its convenience,wide adaptability,no limitation in the device size and shape,low-cost in recoating and repairing aspects.Therefore,more and more attention is focused on theexploringof anti-corrosion coatings with high performance.In this paper,on the basic of traditional coating modification,two-dimensional graphene nano pieces(Gnps)used as the filler,polyether imide(PEI)or epoxy resin us ed as film-former,respectively,the Gnps/polymer composite coatings were prepar ed.The curing temperature of the Gnps/polymer composite coating and the coating process were optimized.The effects of Gnps content on the corrosion resistance of the composite coatings was also studied by employing the surface contact angle measurement,the immersion corrosion test,polarization,electrochemical impedance spectro scopy,and field emission scanning electron microscopy(FE-SEM)method.Gnps antiresistance mechanismand coating failure mechanism was also investigated.The research progression in the paper are as followings:After Gnps,used as filler,corrosion resistance of the Gnps/PEI composite coating and Gnps/epoxy resin composite coating,have been improvedsignificantly.However,it is not good for the coating with higher content of Gnps.For Gnps/PEI composite coating,the optimum content is 1% Gnps jin coating,and the better content is 0.5% for Gnps/epoxy resin composite coating.With the change of Gnps content inthe coating,corrosion mechanism of Q235 steel under Gnps /PEI composite coating and Gnps /epoxy resincomposite coating has changed.With the increase of Gnps content,the Corrosion mechanism transformed from electrochemical process controlling to diffusion controlling gradually.The failure mechanism of Gnps /PEI composite coating is as followings: when the coating was soaked in corrosive media,isolation function of coatings was weakend,and therfore reducing the impedance of composite coatings,coupled with the coating conductivity increasing caused by Gnpsadding the of,the combined effect of two factors accelerated the process of electrochemical corrosion process.Taken all experimental data attended,protection function of Gnps/ PEI composite coating and Gnps/epoxy resin composite coating is not a single affecting factor,but a combined effect of hydrophobic coating,physical barrier,electrical conductivity and other factors.