Study On The Corrosion Inhibiting Performance And Mechanism Of New Organic Polymer Inhibitors For Reinforcing Steel

The corrosion problem of metals,such as reinforcing steel,is becoming increasingly serious,and the selection of inhibitors can easily and effectively reduce the corrosion rate of metals.As a new trend of inhibitors,organic polymer inhibitors have the advantages of multiple adsorption sites,easier formation of multilayer films on metal surfaces,environmental friendliness,and better temperature resistance.However,the existing research and literature on polymers as corrosion inhibitors have a single corrosive medium,organic polymer materials have yield problems and are not cost-effective,furthermore,the current research on corrosion inhibitors is limited by technology,and the specific corrosion inhibiting mechanism of corrosion inhibitors has not been thoroughly studied.There is a huge research space and value for synthesizing and preparing corrosion inhibitors with controllable structure and low price so as to study their corrosion inhibiting performance and mechanism under different environments.In this paper,from the molecular structure characteristics of organic polymer inhibitors,two new organic polymers with promising metal corrosion inhibition effects were synthesized and prepared,which were applied to the corrosion inhibition studies on reinforcing steel in different environments.The corrosion inhibiting properties of the organic polymers were evaluated electrochemically by corrosion potential measurements,electrochemical impedance spectroscopy,and Tafel polarization curves.The surface morphology and elemental content composition of reinforcing steel with and without the addition of organic polymers were investigated using scanning electron microscopy combined with energy spectrometry.Finally,quantum chemical calculations and molecular dynamics simulations were used to explore the mechanism of organic polymers as corrosion inhibitors in depth.The relevant studies and results are as follows:1.Poly[(2,7-bis(3-(dimethylamino)propyl)naphthalenediimide-4,9-diyl)-alt-(9,9-bis(3-N,N-dimethylamino-propyl)-9H-fluorene-2,7-diyl)](PFN-NDIN)was synthesized and prepared,with a molecular structure consisting of aromatic hydrocarbon,fluorenyl and amide groups.The inhibiting effect of PFN-NDIN on Q235 steel in 1 M HCl solution was investigated by electrochemical methods such as electrochemical impedance spectroscopy,Tafel polarization curves and surface analysis tests such as SEM-EDS.The results consistently reflect that the corrosion inhibition efficiency of PFN-NDIN is proportional to the concentration,and both the anode and cathode are affected by the inhibition effect,which is a mixed type of inhibitor.PFN-NDIN spontaneously adsorbs on the metal surface and is affected by both physical and chemical adsorption,which can have a significant corrosion inhibition effect.2.Based on the above study,PFN-NDIN was placed in the simulated concrete pore solution system to study its rust inhibition performance and the mechanism of corrosion inhibition for HRB400 steel.The results show that although the corrosion inhibition efficiency is not as good as that of the hydrochloric acid system,PFN-NDIN still has good corrosion inhibition performance on the steel in the simulated concrete pore solution system,the charge transfer resistance value increases significantly after the addition of this organic polymer,and it is an effective hybrid type of corrosion inhibitor,which is consistent with Langmuir monomolecular layer adsorption.It is also verified that the corrosion exposure of the reinforcing steel is reduced after the addition of the inhibitor,and the adsorption of PFN-NDIN on the reinforcing steel is mainly achieved by the supply of electrons from the aromatic group to the empty d orbitals of the iron atoms on the surface of the reinforcing steel.3.A water-soluble polyfluorene containing aromatic ring and nitrogen atom with fluorene group as the main chain,namely poly(9,9-bis{3’-[(N,N-dimethyl)-Nethylammonium-propyl]-2,7-fluorene dibromide)(PFBr),was synthesized and prepared.The organic polymer shows good corrosion inhibition of Q235 steel in the 1 M HCl solution system,the corrosion inhibition efficiency can reach 96.37% with the addition of 400 ppm PFBr,and this material can be used as a hybrid corrosion inhibitor mainly of the anodic type.Furthermore,the adsorption of PFBr on the steel surface follows Langmuir isothermal adsorption model,with both physical and chemical adsorption occurring.PFBr forms an adsorption film on the metal surface and hinders the corrosion reaction,its molecules mainly use fluorene groups and bromine atoms as the active sites for chemisorption,and adsorb on the metal surface in parallel to facilitate maximum coverage of the metal surface and inhibit corrosion.