Acidic Medium, The Electrochemical Corrosion Inhibitors On Carbon Steel Corrosion Resistance Can Function Study

Corrosion is an extremely serious damage factor in the modern industry.Inhibition has become one of the most widely used methods in the anti-corrosion technology.Adding corrosion inhibitors to the corrosive medium is a simple and effective method to solve the problem of metal corrosion.Because of the advantages of effici-ency and biodegradation,organic corrosion inhibitors have broad application and pr-ospects.A3 steel is an ordinary carbon structural steel, as an important metallic material which is commonly used in industrial environments is particularly vulnerable to corrosion.It has great significance to research A3 steel corrosion behavior and process in acidic medium and adding a corrosion inhibitor, and providing important theoretical references to the actual production as corrosion inhibitor.Immersion test, potentiodynamic scanning (Tafel curves), AC impedance techniques and quantum chemistry calculation were mainly used in this paper to test the corrosion performance by changing the temperature and corrosion inhibitor(benzosulfimide, thiourea, N,N—diphenyl thiourea, sodium dodecyl sulfonate, carbamide,diphenyl carbazide) concentration in H2SO4 medium.Corrosion current density icorr was derived and the inhibition efficiencyη%was calculated by potentiodynamic scanning (Tafel curves).The inhibitor type in study system were determined by the direction of the curves movement, benzosulfimide, thiourea,N,N—diphenyl thiourea were mixed inhibitors, carbamide,diphenyl carbazide were anodic inhibitors.Changing the temperature of the experiment,according to the corresponding inhibition efficiency under the conditions,combinating of Arrhenius equation, by linear fit,the activation energy and pre-exponential factor A were available.Changing the concentration of corrosion inhibitor, by linear fit,the the adsorption model and the corresponding thermodynamic data were determined,which can intuitively reflecte the ease of absorption.In the 5%H2SO4,the inhibition effect of N,N—diphenyl thiourea was best, benzosulfimide, thiourea, diphenyl carbazide, carbamide were followed. AC impedance technology were mainly examined and certifiesed dynamic potential scanning method. The variation of inhibition efficiency were visually reflected by superposing Nyquist diagram of electrochemical impedance spectrum,the radius of the circle was larger,the inhibition effect was more remarkable.Using ZSimpWin software to simulate the corresponding Nyquist diagram,kinetic parameters of the system and the corresponding equivalent circuit were obtained,so that the mechanism of corrosion inhibitors could be more in-depth studied.Quantum chemical calculations were mainly used Gaussian 03 Revision-B03 Software, by the DFT-B3LYP/6-311g method to calculate EHOMO andELUMO values.The performance of corrosion inhibitors were determined from the values of the internal structure of the inhibitors.Combination of the four methods, the mechanism of corrosion inhibitor were researched in greate depth, which can be provided a theoretical basis to the actual production.