| Metal corrosion is a very common phenomenon,which has brought huge losses to the national economy.China's annual economic loss due to metal corrosion accounted for more than 3.3%of GDP.High-speed rail has become a name card of our country and one of the most important means of transportation for people to get around in daily life.With the advancement of the"One Belt and One Road"initiative,the construction of high-speed railway has been continuously extended to the coastal and southeast Asia,and the high-speed railway near the sea needs to face severe corrosion damage brought by high temperature,high humidity and hot Marine environment.SMA490BW bogie steel is a kind of carbon steel with low carbon content,strong damage resistance,strong deformation resistance and large elongation at room temperature.Due to its excellent mechanical properties,it has been used to make bogies for China's new generation of high-speed trains.Therefore,it is very important to study the corrosion mechanism and protective measures of the bogie steel used in high-speed railway to ensure the safe operation and prolong the service life of the coastal high-speed railway.In this thesis,the passive behavior of SMA490BW bogie steel in sodium borate buffer solution with different pH values(8.5-10.5)was studied by electrochemical methods such as potentiodynamic polarization curve,Mott-Schottky analysis,and electrochemical impedance spectroscopy(EIS).The results show that the passivation interval of SMA490BW bogie steel is affected by the pH value of sodium borate buffer solution,and the passivation interval and corrosion potential move to a more negative direction with the increase of pH value.The passivation film of SMA490BW bogie steel in sodium borate buffer solution shows n-type semiconductor properties.Graphene is a two-dimensional carbon nanomaterial with hexagonal honeycomb lattice formed by carbon atoms in sp~2 hybridization.Due to its good chemical inertiality and barrier effect on oxygen and water molecules,graphene has attracted much attention in the field of metal corrosion protection.In this thesis,graphene was dispersed into E51 epoxy resin to improve its protection against metals.Based on electrochemical impedance spectroscopy and morphology analysis,the variation of corrosion resistance of coatings with different graphene content was obtained.The results show that the corrosion resistance is the best when the amount of graphene added is 0.5%.However,due to the poor dispersion of graphene in epoxy resin,the corrosion resistance of epoxy resin is reduced.To solve this problem,an organic liquid-ionic liquid,was selected to improve the dispersion of graphene in epoxy resin.Ionic liquid itself has excellent solubility,non-volatility,environmental friendliness and certain corrosion resistance.A novel ionic liquid-graphene hybrid nanomaterial was synthesized by covalent work between ionic liquid and graphene.Using Raman spectroscopy and electrochemical measurements,it was confirmed that ionic liquid could effectively improve the dispersion of graphene and the corrosion inhibition of coating was greatly improved. |
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