بررسي اثر بازدارندگي تركيبات آلي حاوي اتم هاي دهنده نيتروژن و گوگرد بر خوردگي فولاد ساده ي كربني در محلول يك مولار هيدروكلريك اسيد

چكيده انگليسي :

110 Investigation of the inhibitive effect of organic compounds containing nitrogen and sulfur as donor atoms on corrosion of plain carbon steel in 1M HCl solution Hosein Heydari Soodjani Hosein heydari@ma iut ac ir on October 8 2015 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 8311 IranDegree Master of Science Language PersianDr Keyvan Raeissi Prof Mohammad Ali GolozarAbstractIn this research novel synthesized Schiff bases components Sb1 Sb2 and Sb3 wereinvestigated as corrosion inhibitors for mild steel corrosion in 1M HCl solution These newcomponents contain S S bonds S and N heteroatoms simultaneously For evaluating ofused Schiff bases electrochemical tests tafel polarization and electrochemical impedance were used also weight loss measurements in presence of different concentrations of Schiffbases 10 20 30 40 and 50 ppm were used Corrosion rate of mild steel in weight loss testin uninhibited solution was 1 177 mg cm2 h that in the presence of maximum concentrationofSb1 Sb2 and Sb3 decreased to 0 0976 0 137 and 0 0255 mg cm2 h respectively andinhibition efficiencies for three Schiff bases were91 7 88 3 and 97 8 respectively Theseresults show the significant impression of inhibitors on the corrosion inhibition of mildsteel Tafel polarization measurement results show that inhibitors with the adsorptionperformance impress both cathodic and anodic branches The obtained results showed thatinhibition efficiency increases with increase of the inhibitor concentration Corrosioncurrent density in uninhibited solution was 640 1 A cm2that in the presence of maximumconcentration ofSb1 Sb2 and Sb3 decreased to the 63 5 86 4 and 41 7 A cm2 values respectively and inhibition efficiencies in the presence of these inhibitors were 90 07 86 50and 93 48 respectively The results of EIS experiment showed that in the presence of theinhibitors in the corrosive solution charge transfer resistance values increase andcapacitance of the double layer decreases that is an indication of the adsorption of theinhibitor molecules on the metal surface and replace the water molecules that woulddecrease the attack of the aggressive solution Charge transfer resistance in the absence ofthe inhibitors was 26 cm2 which in presence of the maximum concentration of the Sb1 Sb2 and Sb3 increased to the 348 233 and 515 cm2 values respectively and the inhibitionefficiencies for Sb1 Sb2 and Sb3 were 92 52 88 84 and 94 95 respectively Adsorption ofthe three Schiff bases obeyed the Langmuir adsorption isotherm and high values of thestandard free energy and adsorption equilibrium constant were indications of the strongadsorption of the Schiff bases onto the mild steel surface Tafel polarization experiment wasemployed in the temperature range of 25 55 in absence and presence of the maximumconcentration of the Schiff bases and the obtained results showed that increase in thecorrosion current density in the presence of the inhibitors was extremely lower than thatblank solution which confirms appropriate performance of the inhibitors even at the hightemperatures The calculated values of the corrosion activation energy for the inhibitedsolution were lower than that uninhibited solution that was an indication of the chemicaladsorption mechanism for three Schiff bases Quantum chemical calculations were used tobe compared with the experimental results and some parameters like EHOMO E LUMO E and were calculated and reported Also electron density distribution of the HOMO andLUMO were evaluated Calculated values obtained from quantum chemical calculations didnot show a direct relation with the data obtained from experimental results that is anindication of the complicated process of the corrosion inhibition SEM images from metalsurface showed that mild steel surface in the absence of the inhibitors is extremelydamaged and corroded while in the presence of inhibitors metal surface was smooth andwithout severe damage that confirm the adsorption of

حيدري سودجاني، حسين

بررسي اثر بازدارندگي تركيبات آلي حاوي اتم هاي دهنده نيتروژن و گوگرد بر خوردگي فولاد ساده ي كربني در محلول يك مولار هيدروكلريك اسيد

شيف باز , جذب , آزمون الكتروشميايي , محاسبات كوانتوم شيميايي